How do I initialize (factory reset) the WH-1000XM4 to erase all pairing information?

Disconnect the USB Type-C cable and turn off the unit, then press and hold the Power and CUSTOM buttons simultaneously for at least 7 seconds. The indicator (blue) flashes 4 times, the unit is initialized, and reset to factory settings. All pairing information is deleted when the unit is initialized. After initializing, you may need to delete the pairing information from your iPhone or computer and pair them again. (Page 1)