What to do with XMP files - How to get rid of them

"I did the "Set the option Catalog Settings > Metadata > Automatically Write Changes Into XMP." Fix for the cropping bug and it worked...but only on original RAW files. It didn't work on any virtual copies."

An alternate workaround to the bug is rolling back to version 11.2.  LR generally releases every 8 weeks, so we might expect to see 11.4 this week or next, and hopefully it fixes this bug.

A different point of view. I don't write changes to XMP in Lightroom. I don't have any XMP files on my hard drive. I only use LrC to look at the changes in my raw files. If I view my raw files in File Explorer they appear unedited, but I expect that. If I want to see an edited copy of that file I export from LrC. I have been working this way for years and haven't regretted it. Everyone has their preferred way of working. That's my way, it might not work for others.

I second both suggestions from @richardplondon . In particular, I let Lightroom Classic do all of my file handling (with regards to photos). I view them in Lightroom Classic; I never view them in Windows Explorer. Thus, the .xmp files are invisible to me, and their presence is not a problem.

I don't want to tell you what to do, but my suggestions are twofold - one, to just relax about the presence of these XMPs, they can do you no harm and may even do some good. For example, say you made a Catalog backup yesterday, then today you get a problem that requires reverting to that. Your latest work for each image will have been written to external XMP (aside from virtual copies, Collection membership, a few other matters). So for those images worked on subsequent to this last Catalog backup, latest edits can be read back in from external XMP, fully up to date - you will not have lost all work done after that backup happened.

Second piece of unsolicited advice: what works for me, is to treat the set of folders where my imported images' source files live, as well as PS edited versions etc, as a "black box". I have put LrC in full and sole charge of managing all that. I've told it (in import preset) what the folders and files are to be called and how arranged, strictly date based filing - handle once - that is what I am "paying it to do". There's a saying: don't buy a guard-dog and then bark yourself. LrC is my "front end" for finding anything I want to access, also for anything I might then do with that, including sending out to PS. Exports are made somewhere entirely separate, So I don't have any cause to even peek, let alone meddle, inside those "LrC Library" folders otherwise. Makes for a much easier life! I only have to keep an eye on the available storage space.

It won't do any harm to delete them, and unchecking the option in the preferences stops Lightroom writing to XMP, also for existing files. You can simply delete them in Windows Explorer. Sort on file type, select all XMP files and delete them.