I'm currently using Stacer for this but the size seems a little too big.
The first day I installed Garuda Linux (about two weeks ago I think) I had a problem when I deleted all orphans and had to reinstall, so I'm trying to don't mess things again.
Also, how can I know which orphans should I remove and which not?
Btw, you can also use cache cleaning options in Garuda Assistant. There are both options to clear package cache as well as other ( that is application ) cache.
Stacer is your friend. After you clean your cache (dirty, dirty cache,) just reboot. The system and programs rebuild their caches. It is a always good to do a little blowout now and again.