diff --git a/backends/arm/public_api_manifests/api_manifest_1_6.toml b/backends/arm/public_api_manifests/api_manifest_1_4.toml
similarity index 66%
rename from backends/arm/public_api_manifests/api_manifest_1_6.toml
rename to backends/arm/public_api_manifests/api_manifest_1_4.toml
index 01eb68352c3..25f0c0104fe 100644
--- a/backends/arm/public_api_manifests/api_manifest_1_6.toml
+++ b/backends/arm/public_api_manifests/api_manifest_1_4.toml
@@ -18,7 +18,7 @@ signature = "EthosUBackend.preprocess(edge_program: torch.export.exported_progra
 
 [python.EthosUCompileSpec]
 kind = "class"
-signature = "EthosUCompileSpec(target: str, system_config: str | None = None, memory_mode: str | None = None, extra_flags: list[str] | None = None, config_ini: str | None = 'Arm/vela.ini', external_block_placements: executorch.backends.arm.ethosu.compile_spec.VelaExternalBlockPlacements | None = None, max_scratch_size: int | None = None)"
+signature = "EthosUCompileSpec(target: str, system_config: str | None = None, memory_mode: str | None = None, extra_flags: list[str] | None = None, config_ini: str | None = 'Arm/vela.ini')"
 
 [python.EthosUCompileSpec.DebugMode]
 kind = "enum"
@@ -60,10 +60,6 @@ signature = "EthosUPartitioner.partition(self, exported_program: torch.export.ex
 kind = "function"
 signature = "EthosUPartitioner.register_custom_partition_op(self, op: torch._ops.OpOverload) -> None"
 
-[python.EthosUPartitioner.transform_for_pre_decomposition]
-kind = "function"
-signature = "EthosUPartitioner.transform_for_pre_decomposition(self, exported_program: torch.export.exported_program.ExportedProgram) -> torch.export.exported_program.ExportedProgram"
-
 [python.EthosUQuantizer]
 kind = "class"
 signature = "EthosUQuantizer(compile_spec: 'EthosUCompileSpec', use_composable_quantizer: 'bool' = True) -> 'None'"
@@ -96,38 +92,6 @@ signature = "EthosUQuantizer.transform_for_annotation(self, model: 'GraphModule'
 kind = "function"
 signature = "EthosUQuantizer.validate(self, model: 'GraphModule') -> 'None'"
 
-[python.VelaExternalBlockPlacements]
-kind = "class"
-signature = "VelaExternalBlockPlacements(cmd_data: str | None = None, weight_data: str | None = None) -> None"
-
-[python.VelaExternalBlockPlacements.__delattr__]
-kind = "function"
-signature = "VelaExternalBlockPlacements.__delattr__(self, name)"
-
-[python.VelaExternalBlockPlacements.__eq__]
-kind = "function"
-signature = "VelaExternalBlockPlacements.__eq__(self, other)"
-
-[python.VelaExternalBlockPlacements.__hash__]
-kind = "function"
-signature = "VelaExternalBlockPlacements.__hash__(self)"
-
-[python.VelaExternalBlockPlacements.__post_init__]
-kind = "function"
-signature = "VelaExternalBlockPlacements.__post_init__(self) -> None"
-
-[python.VelaExternalBlockPlacements.__repr__]
-kind = "function"
-signature = "VelaExternalBlockPlacements.__repr__(self)"
-
-[python.VelaExternalBlockPlacements.__setattr__]
-kind = "function"
-signature = "VelaExternalBlockPlacements.__setattr__(self, name, value)"
-
-[python.VelaExternalBlockPlacements.to_block_placements]
-kind = "function"
-signature = "VelaExternalBlockPlacements.to_block_placements(self) -> dict[str, str]"
-
 [python.VgfBackend]
 kind = "class"
 signature = "VgfBackend()"
@@ -138,7 +102,7 @@ signature = "VgfBackend.preprocess(edge_program: torch.export.exported_program.E
 
 [python.VgfCompileSpec]
 kind = "class"
-signature = "VgfCompileSpec(tosa_spec: executorch.backends.arm.tosa.specification.TosaSpecification | str | None = None, compiler_flags: list[str] | None = None, emit_debug_info: bool = False, alias_buffer_mutations: bool = False)"
+signature = "VgfCompileSpec(tosa_spec: executorch.backends.arm.tosa.specification.TosaSpecification | str | None = None, compiler_flags: list[str] | None = None)"
 
 [python.VgfCompileSpec.DebugMode]
 kind = "enum"
@@ -184,10 +148,6 @@ signature = "VgfPartitioner.partition(self, exported_program: torch.export.expor
 kind = "function"
 signature = "VgfPartitioner.register_custom_partition_op(self, op: torch._ops.OpOverload) -> None"
 
-[python.VgfPartitioner.transform_for_pre_decomposition]
-kind = "function"
-signature = "VgfPartitioner.transform_for_pre_decomposition(self, exported_program: torch.export.exported_program.ExportedProgram) -> torch.export.exported_program.ExportedProgram"
-
 [python.VgfQuantizer]
 kind = "class"
 signature = "VgfQuantizer(compile_spec: 'VgfCompileSpec', use_composable_quantizer: 'bool' = True) -> 'None'"
@@ -227,61 +187,3 @@ signature = "get_symmetric_a16w8_quantization_config(is_per_channel: 'bool' = Tr
 [python.get_symmetric_quantization_config]
 kind = "function"
 signature = "get_symmetric_quantization_config(is_per_channel: 'bool' = True, is_qat: 'bool' = False, is_dynamic: 'bool' = False, act_qmin: 'int' = -128, act_qmax: 'int' = 127, weight_qmin: 'int' = -127, weight_qmax: 'int' = 127, eps: 'float' = 1.52587890625e-05) -> 'QuantizationConfig'"
-
-[cmake]
-
-[cmake.arm_runner_add_minimal_executable]
-kind = "function"
-signature = "arm_runner_add_minimal_executable(*, TARGET, SOURCE, OPS_PREFIX, COMPILE_DEFINITIONS=())"
-
-[cmake.arm_runner_add_standalone_executorch]
-kind = "macro"
-signature = "arm_runner_add_standalone_executorch()"
-
-[cmake.arm_runner_configure_ethos_u_platform]
-kind = "function"
-signature = "arm_runner_configure_ethos_u_platform(*, SDK_PATH, SYSTEM_CONFIG, MEMORY_MODE)"
-
-[cmake.arm_runner_configure_linker_script]
-kind = "function"
-signature = "arm_runner_configure_linker_script(*, TARGET, SYSTEM_CONFIG, OUTPUT_NAME=None)"
-
-[cmake.arm_runner_configure_model]
-kind = "function"
-signature = "arm_runner_configure_model(*, TARGET, PTE_FILE=None, MODEL_PTE_ADDR=None, MODEL_PTE_SIZE=None, PUBLIC=False)"
-
-[cmake.arm_runner_configure_runtime_output]
-kind = "function"
-signature = "arm_runner_configure_runtime_output(TARGET_NAME, FALLBACK_DIR)"
-
-[cmake.arm_runner_create_default_selected_ops_libs]
-kind = "function"
-signature = "arm_runner_create_default_selected_ops_libs(*, PREFIX, SUFFIX=None, OP_LIST=None, OPS_FROM_MODEL=None, DTYPE_SELECTIVE_BUILD=None, OUT_LIBS=None, DEPS=())"
-
-[cmake.arm_runner_create_selected_ops_lib]
-kind = "function"
-signature = "arm_runner_create_selected_ops_lib(*, LIB_NAME, FUNCTIONS_YAML=None, CUSTOM_OPS_YAML=None, OP_LIST=None, OPS_FROM_MODEL=None, DTYPE_SELECTIVE_BUILD=None, KERNEL_LIBS=(), DEPS=(), INCLUDE_ALL_OPS=False, PRIM_OPS=False)"
-
-[cmake.arm_runner_define_cache_options]
-kind = "function"
-signature = "arm_runner_define_cache_options(*, METHOD_ALLOCATOR_SIZE=None)"
-
-[cmake.arm_runner_link_minimal_specs]
-kind = "function"
-signature = "arm_runner_link_minimal_specs(TARGET_NAME)"
-
-[cmake.arm_runner_link_registration_libraries]
-kind = "function"
-signature = "arm_runner_link_registration_libraries(*, TARGET, SCOPE=None, BASE_LIBS=(), REGISTRATION_LIBS=(), NORMAL_LIBS=(), SUPPRESS_LIBS=())"
-
-[cmake.arm_runner_require_baremetal_targets]
-kind = "function"
-signature = "arm_runner_require_baremetal_targets()"
-
-[cmake.arm_runner_require_python]
-kind = "macro"
-signature = "arm_runner_require_python()"
-
-[cmake.arm_runner_validate_model_source]
-kind = "function"
-signature = "arm_runner_validate_model_source(*, ALLOW_SEMIHOSTING=False)"