Hi Mike,
There is no way to activate/deactivate blend shapes on your recorded face capture itself. When capturing your own face likeness it only has the animated vertex positions for these recordings, so you can’t in this case deactivate Jaw Open and see the result on your own face.
The blend shapes can be used to drive the animation of other objects, or the strength of Pose Morphs.
To use the blend shapes with Pose Morphs you will have to sculpt each blend shape yourself for your new mesh. There is no way to automatically create the blend shapes pose morphs at the moment.
You can see what a blend shape does by checking the official apple documentation. If you click on one of the blend shape names you will see an image at the top of the page that shows what parts of the face that blend shape controls.
https://developer.apple.com/documentation/arkit/arfaceanchor/blendshapelocation
This post goes over some of this in a bit more detail: https://www.cineversity.com/forums/viewthread/3216/
If you would like a tutorial that covers how to do this in detail then please request one in a new thread, perhaps call it CV-AR Pose Morph Workflow Tutorial, so that we have a record of it rather than it being buried inside another thread such as this one.
I hope the information above helps for now. 
Best,
Kent
