This Seeking Tech guide will show you how to disable the controller speaker audio in Zenless Zone Zero. You can do so by taking the following steps:
1. To start off, open the pause menu.
2. From there, you need to select Options.
3. In the Options menu, you need to select Audio.
4. You then need to move the cursor down to Controller Speaker Volume.
5. Set this setting to zero and then exit the pause menu.
6. You should no longer hear any sound coming from your controller.