Is it possible to temporarily restrict access to apresentation for co-employees? So that after a specified period this restriction will be removed…
Yes. Go to the 'File' menu and then switch to 'Info'. Once there, expand the 'Protect presentation' section and select 'Restrict access', then click the 'restricted access' item. That done, if you have access restrictions enabled and a list of users, click on 'More options'. In a newly displayed window, select the user or users and then, in the section called 'Additional user permissions', select the option 'Presentation expires' and specify the end date.