diff --git a/targets/TARGET_NUVOTON/TARGET_M2351/TARGET_M23_NS/wait_ns.c b/targets/TARGET_NUVOTON/TARGET_M2351/TARGET_M23_NS/wait_ns.c
deleted file mode 100644
index babb7473e3..0000000000
--- a/targets/TARGET_NUVOTON/TARGET_M2351/TARGET_M23_NS/wait_ns.c
+++ /dev/null
@@ -1,62 +0,0 @@
-/*
- * Copyright (c) 2018-2020, Nuvoton Technology Corporation
- *
- * SPDX-License-Identifier: Apache-2.0
- *
- * 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.
- */
-
-#include "cmsis.h"
-#include "platform/mbed_toolchain.h"
-#include "platform/mbed_wait_api.h"
-
-/* Override wait_ns to provide more accurate implementation
- *
- * At high HCLK rate, M2351 cannot provide zero-wait-state flash performance. Besides,
- * cache is off for non-secure land (for internal reason). To fix it, borrowing from
- * mbed-os/platform/mbed_wait_api_no_rtos.c wait_ns, we locate 'delay_loop_code' from
- * flash to SRAM to achieve zero-wait-state performance.
- *
- * NOTE1: With MPU, RAM is marked non-executable. We must mark RAM executable for
- *        running 'delay_loop_code' in SRAM.
- * NOTE2: Cache is on for secure land. This override is necessary only for non-secure
- *        land.
- */
-
-// Cortex-M0+, M3, M4 and M23 take 5 cycles per iteration - SUBS = 1, 2xNOP = 2, BCS = 2
-#define LOOP_SCALER 5000
-
-MBED_ALIGN(8)
-static uint16_t delay_loop_code[] = {
-    0x1E40, // SUBS R0,R0,#1
-    0xBF00, // NOP
-    0xBF00, // NOP
-    0xD2FB, // BCS .-3        (0x00 would be .+2, so 0xFB = -5 = .-3)
-    0x4770  // BX LR
-};
-
-/* Take the address of the code, set LSB to indicate Thumb, and cast to void() function pointer */
-#define delay_loop ((void(*)()) ((uintptr_t) delay_loop_code | 1))
-
-void wait_ns(unsigned int ns)
-{
-    uint32_t cycles_per_us = SystemCoreClock / 1000000;
-    // Note that this very calculation, plus call overhead, will take multiple
-    // cycles. Could well be 100ns on its own... So round down here, startup is
-    // worth at least one loop iteration.
-    uint32_t count = (cycles_per_us * ns) / LOOP_SCALER;
-
-    mbed_mpu_manager_lock_ram_execution();
-    delay_loop(count);
-    mbed_mpu_manager_unlock_ram_execution();
-}