Here is what Dell Latitude D630c can do for un-provision:
The Un-Provision option allows you to reset the Intel AMT configuration to factory defaults. There are three types of un-provision:
What you need for reset to factoty default (easy to check that works, just test that password is admin afther the CMOS clear) is the CMOS clear.
To perform this you need to remove the keyboard and under the keyboard you can find the coin battery, unplug it form motherboard, wait for 8 minutes (at least I tested with 8 minutes) and it works. Note that this will clear all your CMOS so if in the setup is something special write it before the CMOS clear to restore later to the dessired value.