Shrink/Compact vDisk VHD file

When creating a new vDisk, there is a question if you want the file to be dynamic or fixed. When choosing dynamic, the size of the VHD file would grow when demanding more space. Until the size has reached the size of the disk. In my environment I have a dynamic vDisk from 60GB. The VHD file size is 30GB. When deleting files from the vDisk this size doesn’t shrink.