I am trying to change the spring on my rear shock
I have got the shock off but i cannot see how i remove the spring - any advice please
You need to wind off the preload fully. The plate at the other end of the spring can then be rotated and at a certain position it just slips off allowing the spring to be removed. You may need to remove the shock hardware (top hats, pin) to allow the spring to be removed depending on the width of the hardware.
unwind the preload collar as far as it will go. now find the slot in the spring seat at the other end and slide it off the damper rod. the spring can now be removed.
if there's not enough room for the spring seat to lift and slide off then your shock has a spring that's too long and you'll need to compress it before you take it off the bike and bind it with thick cable ties.