How to remove thermocouple from this manifold door?
I was able to get it off by using a hammer and a screwdriver. I hammered a flathead screwdriver onto the end of the clasp-list piece. The clasp is intended to be inserted underneath the black holders and thus can be removed by pulling/pushing it out the opposite direction. 

Here is an image of where the screwdriver should be placed to hit off the U-shaped clasp. This is looking at the same place on the second image of the original question but turned upside down.