Windows docker running out of disk space

By default when installing Docker for windows the docker images file will be installed in the path configured in the Hyper-V manager, which for me happened to be in C:\Users\Public\Public Documents\Hyper-V.

To move the image file you need to:

1. Stop Docker.
2. Move the images file (MobyLinuxVM.xhdx) to the location you wish for Hyper-V to store the image
3. Open Hyper-v and in the setting change the default location to save this image
4. Uninstall and then re-install docker

voila!