De-cap them as you would any spent primer, just use a little more care in doing so. Should not be a big problem. I would be sure to wear safety glasses and use gloves just to be on the safe side.
As to re-using them I would not. When they were first loaded into a case, you pushed the anvil into the primer material and it is ready for any kind of strike. My understanding it takes about 35 lbs of force to set them off. If you should accidentally crush one while re-seating it, it has the chance of going off. And depending on the method you use for seating primers, it then has a chance of setting all the other primers off at the same time as well in the tube or tray. That would not be a pretty picture, indeed.
Even at a cost of $40.00 a thousand, setting off 50 or 100 primers at the same time is not worth the $3.00 or $4.00 you would save by reusing them. Just dispose of them in a safe place and manor.
Good luck and stay safe.
Jim