1. In the DSM Explorer drill down to Queries->Wizards->Obsolete Assets.
2. In the right pane select:
The number of days before you consider an Asset obsolete and the Asset type you want to track.
The Asset Type you want to delete Computers or Users ( you should create a Query for each).
There is also a check box that you can check to automatically delete the machines.
Some Users check this to automatically delete this so the whole process is automated.
Some users wanted to make sure that the Machines or Users are really Obsolete and just have not checked in for a period of time.
Note: I recommend creating 2 Queries, after X months just put them in an Obsolete Group, but after Y months Automatically delete the Objects.
3. Click 'Finish'.
4. Under 'Computers and Users' you will see the Obsolete Computers(X months)/Obsolete Users Groups(X months) created.