Hang about. I was shown a tool that can be used to check accounts on other wikis. I used it and found all the ones I expected plus one other. I just asked what to do about it. I was then told it had no edits and would be assigned to me under SUL. I do not want it, but also do not want people to think it is my account if it gets used. If SUL gives it to me, how would I get rid of it? I'm just being security minded in the same way as I improved my passwd last week.
If the account has no edits, then it will basically cease to exist when we switch to SUL. You will then have an account on all Wikimedia projects with your username. You can't get rid of it, since it isn't really a separate account. That's the whole point of SUL.