Richard No, they can't be deleted. I don't think you need to worry about it. If I didn't live where I do I don't know if I'd know either. You are innocent of doing anything wrong that you should be ashamed of. This is just part of the evolution of language. Every community, group, race, gender, etc has a name that was used in common language but fell out of favour or became a slur. This is simply the evolution of that. Using a no longer acceptable name knowing it to now be unacceptable is a completely different thing.
I'm not judging you and I don't think anyone is. I could have pm'd you and told you but there was already a reply so the post couldn't be changed. I posted about it only to shed light on it so everyone who visits the thread knows. Unfortunately I may have caused you stress doing that. I'm sorry but I think it's not a bad thing. Subconsciously a lot of people have learned something they never would have any other way.
How could they know?
How could you have known?