Is there a way to remove a PC from patch management but still retain the inventory information ?

The reason for this is we have some PCs no longer on our network but I want to retain the hardware inventory info so we can see at a glance if they are fit for use at a later date, but in patch management they are displaying the fact they have lots of missing patches and this is disguising the true patch management statistics.  Is it possible to remove them from the current scope of management but keep an historic inventory ?