Right up to version 2007, there was a really dangerous button labeled “Delete Special”. It seems harmless enough, but in the wrong hands it could be lethal.
If you don’t already know, when you select a collection and click “Delete Special” it would actually delete all the computer objects that were a member of that collection from the database, but not delete the collection itself. Seems like a handy thing, but not when people click it by accident when they meant to delete the collection object.
ConfigMgr 2012 SP1 doesn’t have a delete special button anymore. The feature is still there, but it works a little bit differently.
When you select a collection object and click “Delete”, you are given an extra option to also delete the members of that collection from the database. In effect this is the same as Delete Special. The important thing here is that it’s harder to do it *accidentally*.
An important point to note is that this action will also delete the collection itself. So if you need to do a “Delete Special”, create a new “special” collection and populate it as required. One way to do this would be to set the limiting collection to one that already has all the computers you want to delete, and then create an “Include Collections” membership rule pointing to that same limiting collection.