Wiring Harness At the Firewall

[cpayne5]

Anyone know how to disconnect the engine wiring harness from the firewall? I've already disconnected it from the ECU and 4wd box inside, I just need to dislodge the grommet (or whatever it is) from the firewall. I'm sure it's easy, I just don't want to break anything trying to figure it out on my own.

Thanks.