when some employee lose smartphone/tablet, is there a way to remotely remove settings about their extension? Or the only way is to access the admin console and change its extension password?
Changing the password is the first step. Was the phone/tablet locked with a password, or the data encrypted? If this was a company supplied device, those two things should be mandatory.
Test just changing the extension password. At some point a while back, I tested and found that the extension was still able to connect, not sure if that was fixed and haven't tested recently.
If it was still able to re-provision itself, it may be able to pick up the new password. Haven't actually tried that. Perhaps deleting the extension completely, then creating again?
100% save is delete and recreate the extension if the device state is unclear.
If 3CX should be able to remote wipe a device, I dont think so, we are a PBX and not an MDM solution...