Thanks for your reply!
Time consuming, yes -- I have about a thousand entries in autocomplete,
including several multiples for a person, some of which are years out of
date. To check all of these for what is current would be very time consuming.
Also, there are hundreds of entries I will never use again. And as for
user-unfriendly, every time you delete an entry, it goes back to the top of
the list.
Could not find the username file you suggested (did search of all files
folders containing username). If I do locate it, should I delete the whole
file, or just the contents?