Before deleting a dataset or snapshot, perform a dry run using the -n
parameter. This is to make sure you really want to delete just that
dataset/snapshot and not any dependent ones. ZFS will display the resulting
action when -n is combined with the -v option without actually performing
it:

zfs destroy -nrv mypool@mysnap

Once you are sure this is exactly what you intend to do, remove the -n
parameter to execute the destroy operation.
-- Benedict Reuschling <bcr@FreeBSD.org>