Unfortunately, it wasn’t possible in Veeam One Monitor 5.0. If you assigned an alarm to an object and propagated it to the object’s child nodes, the alarm will work for all of the child nodes and cannot be unassigned from separate child objects.
Today you can exclude specific objects from the alarm assignment scope. For doing it:
Go to the Alarm Management -> Select the necessary alarm -> click Actions -> Edit excludes ->Add -> Infrastructure tree -> Select objects from the virtual infrastructure hierarchy.
It’s another reason to stop using such an obsolete version due to the fact that a variety of improvements have been implemented since that time.
Hope this helps.