First Class:

PIM items deleted on the device will remain on the server.

Contacts deleted on the device remain on the server, but uncheck the "Synchronize entry with device" option.  Result is contact is gone on the device, but remains on the server. 

Caleandar events and tasks deleted on the device remain on the server and with the next sync, are returned to the device.  Result is events and tasks remain on both the server and device.