How can I stop a filter from outputting the default ?

You can either set a custom value through the admin or create a filter and return it false.

This is an example to remove the message above the 'request access' form.

  1. function b3_remove_request_message_text( $text ) {
  2.     return false;
  3. }
  4. add_filter( 'b3_message_above_request_access', 'b3_remove_request_message_text' );