added deletion prompt for installed versions

[Termuellinator]

Hey, i've added a prompt to be able to delete older/unwanted versions/folders, might be handy

[flubberding]

Hey Termuellinator,

Thank you very much for this! This is actually one of the features that is high on my to-do list for this script. Due to the corona-crisis my graduation has been delayed. I'll take a better look, merge all open changes and continue work on the script as soon as I'm done in a few more weeks. Just took a quick look at your changes and it looks good tho.