why does the over center spring have to be removed

If your going to ask the question, you have to trust our answer.

If you have a diaphragm clutch.....Yes,Take the spring off.

It isnt going to be easy to get out, but it should be removed.
You will be much happier with the feel of the clutch.

See that little orange car to the left ?
Factory Hurst 4spd car,now with a diaphragm clutch.
You guessed it, OC spring removed.

You picking up what we're laying down ?