You can remove previously delegated permissions with the zfs unallow command.
For example, assume that you delegated create, destroy, mount, and snapshot permissions as follows:
# zfs allow cindy create,destroy,mount,snapshot tank/home/cindy # zfs allow tank/home/cindy ---- Permissions on tank/home/cindy ---------------------------------- Local+Descendent permissions: user cindy create,destroy,mount,snapshot
To remove these permissions, you would use the following syntax:
# zfs unallow cindy tank/home/cindy # zfs allow tank/home/cindy