You can clear the cookies for YouTube and YouTube only.
You can remove cookies like this in Chromium-based browsers by clicking on the lock in the address bar, cookies then click remove for every YouTube domain.
This will make YouTube lose its state, such as the authuser currently using YouTube.
But please note that, since all Google apps are connected, you ...
You can go to https://get.google.com/albumarchive. Login and then manage old photos and
albums. You can delete them permanently by pressing the more options more options button in the top right corner that looks like three vertical dots. Then press delete.
References and Additional Links
How to view the full size and remove old Google Profile pictures
Do you mean you want to stop the browser suggesting/showing accounts that you can sign in to?
If you want to remove them from sign in options you will need to sign out first.
In the Chrome browser tab, click the key symbol.
This will bring up a list of the stored accounts for Google which you can delete.
You should remove Gmail as as service from your Google Account in order to be able to use an email address from a non-Google service as the Google Account primary email address.
Can the primary email of a Google account be changed to something other than the Gmail address?
How to set my alternate (non-Gmail) address as the account primary?
Can I form a direct URL to a particular Gmail account?
URL to create a new Google document
Google multiple accounts - In URL selection by email instead of by user number