User Configuration > Administrative Templates > Microsoft PowerPoint 2016 > Disable Items in User Interface > Predefined
User
HKCU\software\policies\microsoft\office\16.0\powerpoint
This policy setting allows you to set microphone recording off by default when recording a slide show. By default, microphone recording is on the first time a user records a slide show. If the user turns off microphone recording, then microphone recording will be off the next time the slide show recording window is launched, even if PowerPoint is closed and reopened. If you enable this policy setting, microphone recording is turned off by default. A user can turn on microphone recording when recording a slide show. But, the next time the slide show recording window is launched, microphone recording will be off by default. If you disable or don’t configure this policy setting, the default state of microphone recording is determined by the user. Note: Enabling this policy setting also turns off camera recording by default when recording a slide show. There is a separate policy setting if you just want to turn off camera recording by default when recording a slide show.