Apple TV/FM Radio System - Manual (Page 70)

m To turn off the beep you hear when a new station is
successfully preset, click in the Audio Confirmation of
Presets box to remove the X.
After you’ve finished selecting your preferences, click OK to
implement the changes. (The window then closes.)
m To undo any changes you made since you last opened the
Preferences window, click Reset.
63 Customizing the FM Radio Settings