Answering in a public post as this information may help others as well.
You cannot delete the entire thread. That would be doing a disservice to all the people who have put effort into posting replies to try to help. By removing the text of your post, you've done what you can do. After seeing your request, any respondents that wish to may
edit out the text of their responses as well (or if their posts have been in place beyond the 48-hour editing limit they may
report their posts and ask to have a staff member remove them.)
When registering, this is the text you are shown where you enter your chosen user name:
CHOOSE YOUR USER NAME CAREFULLY. You will use this name to log in and it will be visible to the public in your messages and account information. To preserve your privacy we suggest you enter a nickname rather than your real name or email address. You may use any name you wish provided it does not promote you or your business. Once set, you cannot change your user name yourself.
You can't change your username yourself, but the board admins can change it for you. See:
How can I change my TUGBBS Username?
For future reference, answers to most of your BBS operational questions can be found via the yellow
BBS Help link in the blue navigation bar near the top of all bbs pages. This link takes you to the "Bulletin Board Help" sticky thread in the
About TUG BBS forum.