Domain name, email address need to change

My email address  which was set up by an employee is unacceptable to me but I can't seem to change it.  It has emailname@RIDICULOUSDOMAIN.comcastbiz.net.  It's way too long for anyone ever to remember and I want to scrap it but have been unable to even with the support call.  Can anyone help scrap this name and start over.  It's also the primary user name on the account which I'd like to scrap.