Avoid using the iSNS discovery domain as the means to control storage authorization to specific initiators. Use LUN masking instead if you want to make sure that only authorized initiators can access a LUN.
If you remove a target from a discovery domain while the target is in use, the iSCSI initiator does not log out from this target. If you do not want this initiator to access this target (and the associated LUNs), you must use LUN masking. Removing the target from the discovery domain is not sufficient.