I have just removed the throttle cable from my car, luckily the engine was out at the time. There are two cables, one from the pedal to a bell crank on the bulkhead in the engine bay and then another connecting to the throttle body. There is a cover that needs to be removed, it is held on by two screws one on the top and one on the left hand side as viewed from the front of the car. If you disconnect the cable from the throttle body, pull the outercable from the rubber grommet at the bell crank end and then pull the cable out sideways (pulling it towards the front of the car) and then you can disconnect the inner cable from the bell crank by pulling it upwards. I cannot say how easy this will be with the engine in, but GOOD LUCK!!
i had the same problem on a 1.8 16v.... not for long coz i had to give it to a garage. im pretty sure the inlet manifold needs to come off to gain access and that job seemed best left to an octopus to me!!