[wppb-register] being used to create users

Over the past few days I have been getting a large number of accounts created that appear be getting created by [wppb-register] from Profile Builder, yet I have no forms or pages using these shortcodes however something is allowing people to access one of these and create accounts.

The volume of accounts created is triggering our hosting provider spam filters and knocks out the site for several hours.

Can you tell me how to disable the shortcodes that are enable registration to prevent this happening?

Many Thanks