How to restore the factory settings of trezor Model T is the same as the firmware has not been installed just after buying it.
You can do a Factory reset on https://wallet.trezor.io:
If you have funds in your Trezor, you need to do a Recovery afterwards, so make sure you have your private seed written down and any Passphrase, if you use that for a Hidden wallet. I’d advice you to perform a Dry-run Recovery first, to see if a Recovery later will work.
You need to connect your device in bootloader mode (in order to see the screen mentioned):
Swipe your finger across the screen while simultaneously plugging the cable into your Trezor Model T.
OK, it’s successful. Thank you for your answer!