Hi Damien.maret,
If we understand your requirement correctly, you are willing to close all the tabs open in Adobe Reader DC in one go keeping the Adobe Reader DC to be opened?
Sadly, what you are looking for can not be done in the Adobe Reader DC currently. Either you can close single tab or all at once which would also close the application entirely. This is a default design behavior and there isn't any preferences setting that allows to change it.
We suggest you to use this form to request new features or suggest modifications to existing features- Feature Request/Bug Report Form
Regards,
Akanchha