I understand that I can make a group and not apply any automatic tasks to them, but the patchmanager still shows them as unpatched servers. How can I ensure that servers called SRVNNNNNN do not exist in the patch manager?

Another detail is that these servers have the patchmanager agent installed.

These servers belong to a Citrix system and are its VDAs, so their "life" is short and they are continually created and destroyed.