To remove a participant currently on a waitlist:
Go to Registration
Find the Registration form with a waitlist and click on the View (#) under the Participants column
Check off the registrant(s) you are looking to remove from your waitlist
Click Actions > Activate Participants (located at the top of the table)
Click Activate Participants in the popup and the registrant will be removed from the waitlist
TIP: When viewing registration participants, you can expand the filters box on the left and look for participants where Status = 'Waitlist'