There should never be a need to purge the oil pump on any Harley, but the easiest way to remove all oil from the pump is to simply remove the outer cover. Replace the gasket when reinstalling the cover.
Once the pump is dry, it may require priming to function properly. To prime it, remove the check valve plug (the highest part on the pump) and fill that cavity with oil, then replace the plug and crank the motor.
To do this, you must have the manual.
The oil pump is behind the cam plate, which is behind the gear cover (nosecone).
oil capacity for 1996 dyna wide glide?
Four quarts. It may not use all of four quarts, but close.
the 1999 wide glide takes 3 QT of 20-50 wait oil.
64.5
Dyna Wide Glide
3 quarts.
On the front of the engine
Three quarts.
4quarts filter
34 degrees.