If it's the solenoid underneath at the back of the pump below where the high pressure lines come out to the injectors, that's the advance solenoid.
It can definitely be removed in situ, I've done it many times on that pump - it's an easy job.
There will be a big o-ring sealing against the back of the pump casing and another one that sits on the middle of the solenoid. Sometimes this middle one will "catch" in the pump innards when the solenoid is removed, but this is easily fetched out with a little finger up the pump. Just bear it in mind because if you don't see it, it would be easy to replace the solenoid and not know it was there. I'd have a good fish around with a finger anyway as a matter of course to make sure your variant didn't have any extra o-rings.
While it's out it'd be a good time to clean the mesh filter on the solenoid itself, if you want to test it put 12v across it and it should clonk nicely. It's driven by PWM from the ECU for positions that aren't 100% open or 100% closed.
