You can do this here, with or without the app installed. It cannot be undone.
The mobile number you sign in with. We text a code to it, because nobody should be able to delete your book by typing your number.
Immediately and permanently. There is no 30 day window and no archive.
If you were a client, a professional keeps their own record of an appointment that really happened, with your name removed from it. Their books are their business record, the same as a paper diary, and deleting your account does not reach into it.
Deleting your professional account takes you out of the shop you belong to. If you own a shop, closing your account closes the shop with it, so hand it over first if somebody else is carrying on.
You do not have to delete anything to go quiet. Open the app, tap Me, and turn booking texts off. Turning off "Accepting bookings" takes you out of the directory and leaves your work and your history where they are.