Archive vs delete an athlete: which should I use?

From an athlete's detail page → Edit → scroll to Danger zone.

Archive removes the athlete from your roster and dashboards but keeps everything: workouts, messages, payments, body photos. You can restore them at any time from the Archived tab in Athletes.

Delete is permanent and there's no undo. For an athlete without a Fitiva account, all their history is wiped from the database. For an athlete with their own account, their own workouts, meals, water, check-ins, body progress and records stay in their account, and what goes is your side of it: messages, bookings, your notes, and the plans and goals you set for them. Past payments stay in your Financials for accounting. Use this only when you're sure.

In most cases, archive is what you want.