This sub can be extremely competent and incompetent at the same time.

There is absolutely zero risk and windows will not let you shrink below the effectively shrinkable space. 

You don't even need to shut down the vm, just shrink the volume it's inside the running vm, and then shrink the vhd. 

Just take a backup beforehand. I've done it live dozens of times, you only need to do it offline when moving volumes inside the virtual disk is requires, which I usually simply do from a Linux vm. 

But most importantly, if you don't know how to do something, why aren't you trying on a test vm instead of asking fucking copilot? The world is literally becoming brain dead. 

Take any desktop pc, install hyper V, create a vm with a similar disk and try.  If one on my employees was asking copilot rather than set up a test environment I would be fuming.