If you need to delete shadow copies, you can either delete them in explorer, or use vssadmin, or use wmic

To delete using vssadmin

vssadmin Delete Shadows /For=C: /Oldest
vssadmin Delete Shadows /For=C: /All

for a full list of options

http://technet.microsoft.com/en-us/library/cc788026(v=ws.10).aspx

To delete using wmic

wmic
shadowcopy delete