Snapshots can't be deleted from a client, they're read-only versions of the filesystem.
You can delete them from console, Filerview, or System Manager.
See the man page for the snap command.
snap list volumename
snap delete volumename snapname
or
snap delete volumename -a (to delete all snapshots)
Please use with care if this is a production environment,
you may need those snapshots...
At your service,
Eugene Kashpureff