To remove a participant currently on a waitlist:
Go to the Registration tab
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'