Create a new node within your system tree with a OAS policy of OFF and assign it to that node. Drop the machine in that group, wake it up, good to go, scanning is disabled. If your talking about ODS, just disabled the ODS scan for that new node.
Are you refereeing OAS to be disable for a period of time?
For period of time, That is not possible for OAS, You can disable it through by modifying polices on a single system and assign OAS disable policy.
If you are refereeing ODS to be disable?
Select that system and go to Modify task on a single system and navigate to ODS task, Click on Edit assignment and select below option in first page.
Click on next and select Schedule status as disabled under Schedule tab. ODS task will be disable for particular that system.