Is it possible to create a new account with a different user name and email address but have HTC save my old account if I ever want to use it again?
Also is it possible to change my forum name?
AFAIK No and No.
No saving names, I believe. It would take them effort for virtually no reward. Who would want your name anyway.

I'm sure it's no on the forum name. Either it's not set up that way or, again, it's not really worth their effort.
Just start a new forum account.
Wouldn't it have been easier just to e-mail HTC customer support than to rely on the speculation of those such as me, who really don't know the answer?
Immediate gratification?
wrongway