diff --git a/willow/src/testing_utils/BUILD b/willow/src/testing_utils/BUILD
deleted file mode 100644
index 458411d..0000000
--- a/willow/src/testing_utils/BUILD
+++ /dev/null
@@ -1,157 +0,0 @@
-# Copyright 2025 Google LLC
-#
-# Licensed under the Apache License, Version 2.0 (the "License");
-# you may not use this file except in compliance with the License.
-# You may obtain a copy of the License at
-#
-#     http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS,
-# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-# See the License for the specific language governing permissions and
-# limitations under the License.
-
-load("@cxx.rs//tools/bazel:rust_cxx_bridge.bzl", "rust_cxx_bridge")
-load("@rules_cc//cc:cc_library.bzl", "cc_library")
-load("@rules_cc//cc:cc_test.bzl", "cc_test")
-load("@rules_rust//rust:defs.bzl", "rust_library", "rust_test")
-
-package(
-    default_applicable_licenses = [
-    ],
-    default_visibility = ["//:internal"],
-)
-
-# PRNG
-rust_library(
-    name = "fake_prng",
-    testonly = 1,
-    srcs = [
-        "fake_prng.rs",
-    ],
-    deps = [
-        "//ffi_utils:status",
-        "//willow/src/traits:prng_traits",
-    ],
-)
-
-rust_test(
-    name = "fake_prng_test",
-    crate = ":fake_prng",
-    deps = [
-        "@crate_index//:googletest",
-    ],
-)
-
-# Configuration builder and default testing_parameters for AHE and KAHE.
-rust_library(
-    name = "shell_testing_parameters",
-    testonly = 1,
-    srcs = ["shell_testing_parameters.rs"],
-    deps = [
-        "//ffi_utils:status",
-        "//shell_wrapper:kahe",
-        "//willow/src/api:aggregation_config",
-        "//willow/src/shell:ahe_shell",
-        "//willow/src/shell:kahe_shell",
-        "//willow/src/shell:shell_parameters_generation",
-        "//willow/src/traits:ahe_traits",
-        "//willow/src/traits:kahe_traits",
-    ],
-)
-
-# Testing utilities.
-rust_library(
-    name = "testing_utils",
-    testonly = 1,
-    srcs = [
-        "testing_utils.rs",
-    ],
-    deps = [
-        ":shell_testing_parameters",
-        "@crate_index//:rand",
-        "//ffi_utils:status",
-        "//willow/src/api:aggregation_config",
-        "//willow/src/shell:kahe_shell",
-        "//willow/src/shell:vahe_shell",
-        "//willow/src/traits:ahe_traits",
-        "//willow/src/traits:kahe_traits",
-        "//willow/src/traits:messages",
-        "//willow/src/traits:prng_traits",
-        "//willow/src/traits:vahe_traits",
-        "//willow/src/willow_v1:willow_v1_client",
-    ],
-)
-
-rust_test(
-    name = "testing_utils_test",
-    crate = ":testing_utils",
-    deps = [
-        "@crate_index//:googletest",
-    ],
-)
-
-rust_cxx_bridge(
-    name = "shell_testing_decryptor_cxx",
-    src = "shell_testing_decryptor.rs",
-    deps = [
-        ":shell_testing_decryptor",
-    ],
-)
-
-rust_library(
-    name = "shell_testing_decryptor",
-    srcs = [
-        "shell_testing_decryptor.rs",
-    ],
-    deps = [
-        "@protobuf//rust:protobuf",
-        "@cxx.rs//:cxx",
-        "//ffi_utils:status",
-        "//shell_wrapper:shell_types_cc",
-        "//willow/proto/willow:aggregation_config_rust_proto",
-        "//willow/proto/willow:messages_rust_proto",
-        "//willow/src/api:aggregation_config",
-        "//willow/src/shell:ahe_shell",
-        "//willow/src/shell:kahe_shell",
-        "//willow/src/shell:parameters_shell",
-        "//willow/src/shell:single_thread_hkdf",
-        "//willow/src/shell:vahe_shell",
-        "//willow/src/traits:ahe_traits",
-        "//willow/src/traits:kahe_traits",
-        "//willow/src/traits:messages",
-        "//willow/src/traits:prng_traits",
-        "//willow/src/traits:proto_serialization_traits",
-        "//willow/src/traits:vahe_traits",
-    ],
-)
-
-cc_library(
-    name = "shell_testing_decryptor_cc",
-    srcs = ["shell_testing_decryptor.cc"],
-    hdrs = ["shell_testing_decryptor.h"],
-    deps = [
-        ":shell_testing_decryptor_cxx",
-        "@abseil-cpp//absl/memory",
-        "@abseil-cpp//absl/status",
-        "@abseil-cpp//absl/status:statusor",
-        "//shell_wrapper:shell_types_cc",
-        "//willow/proto/shell:shell_ciphertexts_cc_proto",
-        "//willow/proto/willow:aggregation_config_cc_proto",
-        "//willow/proto/willow:messages_cc_proto",
-        "//willow/src/input_encoding:codec",
-    ],
-)
-
-cc_test(
-    name = "shell_testing_decryptor_test",
-    srcs = ["shell_testing_decryptor_test.cc"],
-    deps = [
-        ":shell_testing_decryptor_cc",
-        "@googletest//:gtest_main",
-        "@abseil-cpp//absl/status",
-        "//ffi_utils:status_matchers",
-        "//willow/proto/willow:aggregation_config_cc_proto",
-    ],
-)