If you want to completely disable client registration (a picu Pro feature), you can use the following snippet to do so:

/**
 * Disable client registration
 */
add_filter( 'picu_collection_bouncer', '__return_false', 99 );

Please note, that everyone with access to the collection link will then see the same selection and will also be able to make changes to that selection (until it is approved).

Still having issues?

In your WordPress Admin go to picu > Settings > Debug Info and send the contents of this page and your questions to support@picu.io.