Help replacing blower motor assembly?

Hi all!
Newbie here with my first post. Have an 07 Prius with 225K. I've been having problems recently with my heater turning off and on randomly, and through priuschat discovered it's likely the blower motor going bad. Toyota wanted $350 in parts/labor, so I bought a new one online and am trying to do it myself. Following posts here, I've gotten to the point of disconnecting the old motor but I'm unable to release the wiring harness/connector (picture below of the connector). I believe there is some kind of release tab or something, because it feels like I'm going to pull the wires out of the harness if not. Anyone have any experience with this or advice?

 

Thanks Patrick, but I haven't been able to move anything around (below, above, or next to) that rectangular wiring connector. I've spent a couple hours with various tools and techniques but still no dice.

Here are some pics of the socket on the replacement blower motor. There looks to be a slim, rectangular hole/slit just to the left of the 2 electrical connectors. This is possibly where the wiring harness locks in?

 

Thanks everyone. I was able to get the tab to release after giving up on all the different screwdrivers and tools I was trying to use and just slid a thin nail in the opening to the left of the harness to leverage against the connector and push the tab toward the connector (see last pic from northwichita) which released it. Reassembled and everything works perfectly.

I really appreciate all the help!