Flashed Grandstream 2170 w/ 3CX firmware.. How to undo?

[actinc]

As title states, originally put the 3cx firmware on 2170 phone.. Now trying to use on different brand pbx and it's not provisioning.
Tried factory resetting and upgrading firmware from the grandstream site 1.0.9.127 but still showing 3CX here
The screenshot is how it's set after a factory reset

 

[cobaltit]

So the 3CX Auto Provision is a normal configuration option, it's not specific to the 3CX firmware. You don't mention how you provisioned the phone with 3CX or how you are trying to provision it with the other PBX. Fill in those details and then maybe someone can offer some suggestions.