In order for GroundWork Monitor to build an external to be used by the gdma client, it needs to be associated with a monarch group either individually or by hostgroup membership, so that it has a build folder specified where it will create the external the gdma agent will use. When a gdma host auto-registers, it is placed in the landing hostgroup group, "Auto-Registration".
Once the host is in the Auto-Registration hostgroup, it becomes a member of the auto-registration monarch group, which has a build folder /usr/local/groundwork/apache2/htdocs/gdma.
If you remove a gdma host from the Auto-Registration hostgroup, it loses it's association with the auto-registration monarch group, so an external file is not built for the host, and when the gdma host next polls the GroundWork server and doesn't find one, the agent thinks it is decommissioned, and deletes it's external, and reverts to using gdma_auto.conf, which starts the auto registration process again.
So if you do wish to move hosts out of the Auto-Registration hostgroup, you need to place it in another hostgroup, like gdma_configured for example, and this hostgroup then needs to be assigned to the windows and unix gdma monarch groups, or modify "Auto_Register_Pass" and "Auto_Register_User".
To stop auto registration, modify following lines in gdma_auto.conf:
As explained above, setting Enable_Auto = "off" in the host externals file in the gwmon_<clientmane>.cfg will not stop auto registration.
That said, you could leave the host in Auto-Registration hostgroup, and assign the host to your other hostgroup at the same time.