If you wish to return the Phantom app to its default state and erase all data, you can do so using the reset app feature. However, it's important to note that this action will wipe out all your data, including seed phrases. To avoid losing access to your wallets, ensure you have a backup of the seed phrase before proceeding.
To reset the app go to Settings > Security&Privacy > Reset app.
After the reset, the app will present you with an onboarding screen. You can either create a new wallet or use a seed phrase to import your previous wallets.