This is a great report.
We found a small bug based your feedback.
As you remove motion, the motions on shoulder and hand will be removed but the elbow motion remains.
This is probably why you character's hand still moves after remove motion.
We will fix this ASAP.
Meanwhile, you can send us your project to help us identify if the problem you encountered is what we identified.
You can sent your project to firstname.lastname@example.org
if it is available.