See this article: Where is the Registrant List located?

1. Scroll down to the registrant data section - note that there are a total of 47 registrants
2. Select the registrants that you want to delete by clicking the checkboxes in the blue column
3. Click the Bulk Delete button

Note: Registrants who have made payments cannot be deleted - recommend: mark their status as Not Attending and exclude that status from your reports using a filter.

The Bulk Editor first checks to make sure you are not deleting registrants who have made a payment.  If registrants with payments are found, the following screen appears and lists all registrants who WILL NOT be deleted.  If the list is correct, click the Continue button.  If not, click the Close button.

Visually, scan the list to make sure you want to delete the registrants in the list.  There is NO UNDO for deleted registrants - How do I view deleted registrants?

1. Note that the registrant count is now 45 - 3 were selected for deletion, but 1 had a payment and was not deleted