okay, thanks a lot. Luckily I'm a fast learner. I logged in to my server and found phpMyAdmin and the table zp_administrators and dropped it.
I'll re-run setup and hope everything works out well this time. I read somewhere on the forum that I should load the folders album, backup, themes (I customized a default theme)and cache to my folder Zenphoto on the root of the server BEFORE running setup, so I don't loose my albums and photos I already made. Is that what I should do in my case now also?
I made a backup of these folders before removing my zenphoto.