Formatting a Lenovo Q350 requires the default or custom pin, whatever is present on your phone currently. If you have changed the pin lock since your purchase, you will require that for the process to complete. If its unchanged, you should check what was the default pin from the phones manual. After getting the pin, you should go to the settings and find the reset option, which most probably is in the storage or general settings. Pressing reset will ask you for the pin and then it will simply reset your phone. Please backup your data as it may format the phone memory in the process.