rsvpBOOK has 2 versions of the Admin Dashboard.  Which one do you have?

Turning off the ability of the registrant to edit their registration page also turns off the prompt for a password on their registration page.  No editing, no password needed.

NOTE:  If you have an event with many choices of tickets and session options AND anticipate many registrants, this is usually not a good idea because people change their minds; if they can't change their registration themselves, they will call you and you will have to do it for them.  Turning off editing for a registrant DOES NOT affect your ability to edit their registration. You can still do so.