Disabling Security Groups In a Zone
This is one time decision, unless you do not have any guest VM etc. created you may not want to change it.
I see this settings is saved in the "data_center" table in "is_security_group_enabled" column.
Please note that, any direct change in the DB needs CloudPlatform service restart. Also, we do not recommend modifying DB. Please ensure backup of DB etc. are ready before trying this last option.