I've misspelled user name when installing (XUbuntu 11.10) and would like to rename if possible. How can it be done safely?
Safely? Don't rename at all. Instead, (make sure the user is logged out first) create a new user with the correct username, rename the old home directory to the new username and chown -R the folder to the new user.
This assumes that you're not using encrypted homes. That would require some different steps, but since I haven't done that myself, I'll leave that to someone else.