guest_name = false will disable name prompt
guest_email = false will disable the email address prompt
guest_location = false will disable the location prompt
guest_referral = false will disable the "where'd you hear about this BBS" prompt

Note, at minimum, I do recommend prompting for the guest's email address so that if they send the sysop feedback (e.g. ask a question), they at least have some hope of receiving a reply.