To remove an athlete from your competition, navigate to the "Registrants" tab of your competition dashboard, circled in red in the screenshot provided.

Your list of registrants will populate by division. Find the athlete you need to remove, and select to "Edit Details", circled in red in the screenshot provided.

From there, select "Delete".

Please note that deletions are irreversible and will require an athlete to completely re-register, and any entered scores on the leaderboard will be lost. Deleting an athlete also does not refund their registration. See this article for guidance refunding an athlete.