I always delete the movie after I have seen it and in plex there is an option when where you can delete the movie but unfortunately it only deletes the movie and not the folder / subtitle file which means you have to go to the server and delete everything manually and try to remember which movies you have deleted which can be quite frustrating.
I would have loved to have an option when deleting a movie inside plex that a box appears asking if you also want to delete the folder? with a (Yes / No)
There’s already a feature suggestion asking for that exact functionality. I suggest you comment/vote in that thread in order to avoid distracting/dispersing votes/attention.