I’d recommend being very careful. I recently sold a Mini 3 Pro with RC and was unsure about the unbinding process and how to clear all my data from the drone and controller. I watched several videos and read forum entries and ended up with this list of things to do:
Charge up batteries/remote
Remove accessories
Remove SD cards
Remove IDs
Format internal memory
About: Reset all settings/Clear all data
Profile: Device management: Value add - unbind, Account: remove device from account
Profile: Settings: Scroll down and logout
Forget WiFi/reset network settings
Reset to factory
I demoed the drone to the purchaser and then went through the list before handing it over to him. He was new to drones and during his setting up process back at his home, he found he was still logged in to my account! At one point, he was close to deleting my account but, fortunately for me, realised it might not be a good idea. He contacted me and we managed to sort things out between us.
I later contacted DJI to see if they could explain what might have happened but they were unable to suggest anything apart from perhaps I didn’t log out. I know I went through the list above very carefully so it remains a mystery, but I shall be even more careful the next time I sell a drone.
Just to add, I realised there was some redundancy in the list I created. Resetting to factory defaults should (I’d have thought) have reset the network settings. However, I’ve learned (the hard way) that assumptions can be wrong so I tried to make the list exhaustive.
I think it would help users a lot if DJI had a simple “Transfer Ownership” option that did all of the necessary work behind the scenes and thus avoid the somewhat confusing process that is needed now.