Restrict changes to PowerPoint presentations - Microsoft Support
https://support.microsoft.com/en-us/office/restrict-changes-to-powerpoint-presentations-825d94ed-049b-4785-acf6-8adde845b661
WEBSelect File > Info. Select Protect Presentation, point to Restrict Access, and then select Restricted Access. In the Permission dialog box, select Restrict permission to this presentation, and then select More Options. Under Additional permissions for users, select the This presentation expires on check box, and then enter a date. Select OK twice.
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