Flick it out with a small screwdriver!!
Remember which way it is sprung. If you put it in the wrong way then it will alwaus come loose!!
To get it back in afterward the stick the spring in loose and use the small screwdriver to move it up a few notches. EASY PEASY!!!
Check that it working okay by loosening the headset with your hand and letting go. It should re-tighten itself.
DO NOT overtighten the Headset spring. If its not loose enough then your crushing your bearings and it will wear them quicker.
It should be sprung just enough that it can't ever come loose and cause play in your headset!!
