http://blog.acarter.co.uk/2012/02/server-2008-vss-cannot-remove-snapshot/
I tried to use vssadmin by doing a ‘vssadmin list shadows‘ which sure enough showed me the copy, but when trying to delete it with the ‘vssadmin delete shadows /for=g:‘ , I was returned the error:
Error: Snapshots were found, but they were outside of your allowed context.Try removing them with the backup application which created them.The fix? Use the ‘diskshadow‘ command, then ‘delete shadows all‘ – fixed, it can now be moved from the GUI.