1. Start Tails from the USB stick on which you want to delete the Persistent Storage.

  2. In the Welcome Screen, keep the Persistent Storage locked.

  3. Choose Applications ▸ Tails ▸ Persistent Storage.

  4. Click Delete in the right of the title bar.

This technique is fast but might not prevent a strong attacker from recovering files from an old Persistent Storage using advanced data recovery techniques.

To securely delete the Persistent Storage, you have to securely delete the entire USB stick, which is a much slower operation.