Can you make Fields inactive?

We are doing a data cleanup exercise, getting rid of old artifacts including custom forms and fields. I can see ~300 fields not on any existing custom form, so that's an easy clean-up area. But...

My question to the group: I can see ways to make custom forms "Inactive" (versus deleted, which we don't want to do), and values within fields "Inactive", but can't see a way to make fields themselves "Inactive". I can only see the option to delete.

Can someone confirm I am not missing something? I'd prefer to make inactive if I can, but that might not be possible.

Thanks in advance,

Ryan