I have only done it once, but on mine, the end of the outer cable had a sleeve that passes over the odd shaped bit which goes into the rear of the backplate.
Lots of WD40, and a set of tap pliers, rotating the sleeve back and forwards to work the oil in, and get it loose, and it then just slides off. If you are replacing it, you could use a bit of heat, but I did not need to, and was able to take it off, and free up the cable which was sticking, without having to replace the whole thing.