Once the FSR is fully placed, it is secured to the HVAC box using a plastic clip/detent.
To detach, just pull the fastening clip in the opposite direction and remove the FSR. To disconnect the electrical plug, compress the two symmetrical retention clips on the connector.
To help you identify the two stronger wires that connect the outlet to the blower motor, I've included some images in this email.
In case you were wondering, I "send" 12v to the blower motor during testing by using a little Lion battery with a pair of crocodile clipped wires.
It makes no difference either way you connect the 12v supply to the blower motor if the plug is detached from the FSR. Connecting it in a "backwards polarity" manner will just cause it to spin in the opposite direction of original rotation.