You can permanently delete your PokéTriss account and all associated data at any time. Here's how, what's removed, and how long it takes.
Open PokéTriss and go to Profile → Settings → Delete Account. Confirm, and your account and data are removed immediately and you're signed out.
No longer have the app? Email support@poketriss.app from your account address with subject "Delete my account." Completed within 30 days.