Help with Hyper-V !!

Help! I'm not as proficient with Hyper-V, as I am with ESXi, and I inherited this system to support.

I need to free up space on the drive that holds the Virtual Disks - I went to reboot one of the VirtualMachines, and it went to an 'off' state rather than rebooting. I attempted to Start the VM, and it said, "Could not initialize xxxxxxxxxx" (more on that error at bottom). I only have 48GB free on a 1TB volume. One of my 2 VMs says that a snapshot is running, which is why I can't currently move the Virtual Disk file

IN the 'snapshot' window, it shows me something like this:

_______________________________________________________________
--name of VM -- 7/24/2017
|
------->NOW (You are here)
_______________________________________________________________

I have a "VHDX" file that equates to this exact date (july 24), and it's 20GB in size. (but its not growing like I thought a Snapshot should..) its always been 20GB. In the same directory, I have a "AVHDX" file that has the current date on it, and its 600GB in size - I know I shouldn't touch that one.

What can I do to get more space back..? Should I hilight "-name of VM- 7/24/2017-" and select "delete snapshot"?

Regarding the error when rebooting the VM: the windows Event viewer said that the VM "Quit unexpectedly", and other errors say, "Faulting Module = vmwp.exe" and "Faulting MOdule = kernelbase.dll" and an exception code of 0xe06d7363

 

Orignal poster here: I looked at a few videos.. Remember I said I inherited this system.. apparently both of my VMs have been running snapshots since ****August of 2017***. The disk-file is 20GB like it should be, but the 'differencing' file is 600GB!!!. On the other VM, the disk file is 20GB, and the differencing file is 100GB. The guy who built this server put all the disk files on C:\ which only has 48GB remaining of 1T.