In the app
Open the app, go to Settings → Security → Delete Account, enter your password and confirm.
What happens?
You are signed out everywhere and local data is erased. Encrypted server data is kept for 30 days so you can restore by signing in and choosing “Restore account”; after 30 days the account, synced data and devices are permanently erased.
Guest mode
If you never created an account, your data lives only on the phone; you can delete the guest workspace in Settings or simply uninstall the app.
Without access to the app
Use in-app support or email cidna.app@gmail.com to request account deletion.