You can delete your account in the app (Profile → Delete account), or here. Deleting removes your account, birth details, family profiles and all chats permanently. It does not cancel a subscription: cancel it in your Apple or Google account first.
If you signed in with Apple using “Hide My Email”, delete your account in the app, or email hello@thecelestic.com from the address linked to your Apple ID and we will delete it within 30 days.