Can I Format/Erase This Disk?

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.

Here are some links to show the architecture of the drive in Disk Utility as well as a look at the drive from Finder.

This is the hierarchy in disk utility:

This is the FIRST instance of CRUCIAL in Disk Utility, as seen in the Finder:

This is Untitled2 in the Finder:

This is the SECOND instance of CRUCIAL in Disk Utility, as seen in Finder, and the one that worries me because of all the folders and such:

And this is Update in the Finder:

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. Any help would be appreciated.

Thanks!

Solution 1:

From your comment, it looks like you've got 2 SSDs in the iMac, an Apple 128GB and a Crucial 256GB. Based on your Finder screenshot, they both appear a bit messed up (it shouldn't show the "- Data" part).

I'd recommend restarting into Recovery (based on which OS you want to install, there are a few options: https://support.apple.com/guide/mac-help/use-macos-recovery-on-an-intel-based-mac-mchl338cf9a8/mac). Once you're in Recovery mode, I'd open Disk Utility and fully erase both drives (ensure "Show All Disks" is enabled in the View menu and erase the "Apple SSD..." and "Crucial_..." drives). Make sure to format them with GUID partition maps and APFS (unless you've chosen to install the iMac's original OS, in which case it may need HFS+). Then, back out of Disk Utility and reinstall macOS to whichever drive you want.

Note: It may be possible to open the iMac up and install a different drive in the drive slot, as it appears the previous owner had done (installing a second SSD).