Resetting user id numbers

Is there a way to reset the number of registered users from the history of registered users to just the number of users actually still registered?

I’m probably not wording this very well. I’ll give an example.

I’m user id #1. My co-admin is user id #7. All other users were wiped when my host had server errors last week, and I had to remake my co-admins account. Since there’s obviously not seven people, can I get her id to be #2?

Thanks for anyone who can help.