To remove a client, head over to Clients > All Clients. Find the client you want to delete, click on Actions, and choose Delete Client.
Just a heads up—this action is permanent, and all of their data will be gone for good.
But, if you’d rather keep their info on file in case they rejoin your program, you can simply choose to 'Cancel their membership'. This will archive the client, allowing you to re-activate them later if they come back!