1. At the bottom of the screen, the device will display the "Erase iPhone" option. Not all versions of iOS will display this option, and older versions do not provide this option. In this case, you must directly use 4uKey to get the entry.
2. You need to prepare the details of the AppleID in order to erase it locally. When it appears, click Erase iPhone. The screen will display a warning about data loss. Tap Erase iPhone again. When prompted, enter the iCloud account password. This will sign the AppleID from the iPhone and trigger erasure.