Hyper-V snapshots, why are they still there..??

When you create some snapshots (or checkpoints named in Microsoft SCVMM) within Microsoft Hyper-V, there’re some new files within the folder where the VHD file is located. The snapshot (checkpoint) files have the extension .AVHD. When you delete these snapshots (checkpoints), the .AVHD files are still there…but why? The only solution to automatically delete these .AVHD files is to Shutdown or Turn Off the virtual Machine. As you can see, all the . AVHD files are gone after a shutdown.