The old instructions where to connect to DJI Assistant 2 go to Firmware update and select reset factory defaults. Not an available option anymore. So what is the secret method now?

All you need do is remove it from your account. You could format the internal memory. Then - Profile/Device Management/*model*/Remove Device from Account

Turns out, after a long hold on chat, it is far more complicated than just that data and your logins remain if you just un-bind. To ensure your WiFi accounts and password, your RTK NTRIP and D-RTK-2 logins are erased and your flight logs, along with resetting the controller to factory default. Just unbinding it leaves all that. Turns out you must go to the drag down, then select the settings menu. Then select the the little gear symbol. Another menu pops up, you scroll down several levels to reset menu. You then have to select reset WiFi, then reset apps, then reset controller and data. You need to do this before you unbind, otherwise you have to log back in, reenter the WiFi settings and password then bind, go through it all again. I liked the earlier method of DJI assistant 2 Enterprise  better.

Dogpilot Posted at 12-10 12:13
Turns out, after a long hold on chat, it is far more complicated than just that data and your logins remain if you just un-bind. To ensure your WiFi accounts and password, your RTK NTRIP and D-RTK-2 logins are erased and your flight logs, along with resetting the controller to factory default. Just unbinding it leaves all that. Turns out you must go to the drag down, then select the settings menu. Then select the the little gear symbol. Another menu pops up, you scroll down several levels to reset menu. You then have to select reset WiFi, then reset apps, then reset controller and data. You need to do this before you unbind, otherwise you have to log back in, reenter the WiFi settings and password then bind, go through it all again. I liked the earlier method of DJI assistant 2 Enterprise  better.