Hi, deleting a character isn't possible. If you want to start a new one, you'll have to die in-game, which is currently possible by either being executed by your faction or a faction with the proper privileges at your location, or by flying into a star or black hole (which will require you to pilot a ship).
Are you sure that your account actually exists? You could check that by trying to use the "lost password" feature on the front page. Either you get an "invalid email" error meaning that your account doesn't exist, or you should get a new password into your email.
If that still doesn't work, send me an email to firstname.lastname@example.org containing your signup email and your handle and I'll check it out.