I purchased an iMac (Catalina) from a guy on FB a few months ago and I recently found some of his old files on an internal Crucial 250GB SSD. I got in touch with him and asked if he needed any of them and he doesn't.

How do I know if I can reformat/erase the drive so that I can make use of all the space available on it?

I can't tell if there are some system files on there or something that will make the Mac crap the bed and cause me a big headache. Any help would be appreciated.

I can post screenshots (I think, if they're not regulated on here) if that will help.

Ultimately, I'd like to find out if I can erase the Crucial SSD drive so that I can use it without messing anything up.

Thanks!