The most common way to deactivate a scenery package is to either remove it from the Community folder, and restart the sim, or to use the Content manager to delete a package.
I found that a specific package can be deactivated without deleting the package by editing the Content.xml:
<Package name="asobo-airport-eg78-outskerries" active="true"/>
can be edited to...
<Package name="asobo-airport-eg78-outskerries" active="false"/>
and then the outskerries package will be deactivated upon restarting the sim, and the actual package will not be deleted from the computer.
My idea is to allow the content manager to deactivate a package by marking the 'active' as false (not just deleting the package). Doing this in-sim will save time as the sim would not be needed to restarted. And time would be saved as the package could be reactivated without needing to re-download it. After altering the Content.xml, then the scenery would need to be reset, just as deleting a package does.
This would also allow "star" content to be overridden, as they could be deactivated should a developer come up with an alternative scenery, and then later switching back to activation if wanted, all without restarting the sim.