How do I get rid of extra runtimes?

Thanks for the explanation and advice.
I think I have enough to get rid of the extra stuff on my system (essentially to delete and reinstall), so I’ll describe below what I plan to do, and I’ll mark it as a solution once I’ve tested it. I’ll edit the post if I or you find something wrong with it, and then move on.

I will eventually try pp because it’s very useful to me and because it worked for me on multiple computers with ActivePerl 5.26. I’ll report on that much later in a different thread.

Thanks again for your patience and support; I really appreciate it, especially since I’m on a Free Tier subscription.

So here we go, my take on how to clean and reinstall a runtime of ActivePerl 5.36 in a fixed location for multiple users on a Windows 10 PC:

  1. Make sure your Perl project is ready on the ActiveState Platform, because you’ll restart from there.
    (Check the documentation for state push if you’re not sure.)
  2. Run state clean uninstall from each user account on the system (at least for every user that may have had the State Tool installed).
  3. Manually delete AppData\Local\activestate for each user (in case state clean uninstall didn’t do it).
  4. Manually remove all references to ActiveState from system and user PATH variables.
  5. Run state-remote-installer.exe from one user account, presumably an admin account that will be used to keep State and Perl up to date. The rest of this procedure must be done from this account.
  6. state auth
  7. state checkout <your ActiveState organization name>/Perl-5.36.0-Windows --runtime-path C:/Perl
    Feel free to substitute your real project name and the path where you want to install Perl.
  8. state clean cache (to remove cached runtimes, because this procedure is to install only one Perl, shared by multiple users, in C:\Perl).
  9. Manually add C:\Perl\exec to the system PATH.
    Adjust according to your Perl installation folder if necessary.
    See FAQ :: ActiveState Platform Documentation for more details

A note on PATH:
I and at least one other user successfully ran ActivePerl with other folders than Perl\exec in the PATH. There might be valid reasons to do that, but it’s not recommended, probably not supported, and it may fail at some point.