diff --git a/audio/utility/audio_frame_operations.cc b/audio/utility/audio_frame_operations.cc
index 1b936c239b..47f7b7155c 100644
--- a/audio/utility/audio_frame_operations.cc
+++ b/audio/utility/audio_frame_operations.cc
@@ -72,22 +72,6 @@ void AudioFrameOperations::Add(const AudioFrame& frame_to_add,
   }
 }
 
-int AudioFrameOperations::MonoToStereo(AudioFrame* frame) {
-  if (frame->num_channels_ != 1) {
-    return -1;
-  }
-  UpmixChannels(2, frame);
-  return 0;
-}
-
-int AudioFrameOperations::StereoToMono(AudioFrame* frame) {
-  if (frame->num_channels_ != 2) {
-    return -1;
-  }
-  DownmixChannels(1, frame);
-  return frame->num_channels_ == 1 ? 0 : -1;
-}
-
 void AudioFrameOperations::QuadToStereo(const int16_t* src_audio,
                                         size_t samples_per_channel,
                                         int16_t* dst_audio) {
diff --git a/audio/utility/audio_frame_operations.h b/audio/utility/audio_frame_operations.h
index 2a5f29f4f5..26a2d5e7d1 100644
--- a/audio/utility/audio_frame_operations.h
+++ b/audio/utility/audio_frame_operations.h
@@ -33,18 +33,6 @@ class AudioFrameOperations {
   // `result_frame` is empty.
   static void Add(const AudioFrame& frame_to_add, AudioFrame* result_frame);
 
-  // `frame.num_channels_` will be updated. This version checks for sufficient
-  // buffer size and that `num_channels_` is mono. Use UpmixChannels
-  // instead. TODO(bugs.webrtc.org/8649): remove.
-  ABSL_DEPRECATED("bugs.webrtc.org/8649")
-  static int MonoToStereo(AudioFrame* frame);
-
-  // `frame.num_channels_` will be updated. This version checks that
-  // `num_channels_` is stereo. Use DownmixChannels
-  // instead. TODO(bugs.webrtc.org/8649): remove.
-  ABSL_DEPRECATED("bugs.webrtc.org/8649")
-  static int StereoToMono(AudioFrame* frame);
-
   // Downmixes 4 channels `src_audio` to stereo `dst_audio`. This is an in-place
   // operation, meaning `src_audio` and `dst_audio` may point to the same
   // buffer.