Originally Posted by Andrew R Stewart

Typically one has to pull the lever/shift spool/pod out of the handle bar bracket to allow for a hex wrench to get past the lever/pod and be able to engage the bolt inside that acts on the clamping bits. So if you can get enough cable slack to then pull the lever/pod out of the bracket you're fine. But if you can't and if the cable routing pathway is hidden (did I say how I dislike internal routing...) and a section of casing can't be pulled from a cable stop (and thus gaining a lot of cable slack) you'll likely have to detach the cable from it's anchor bolt.

I will often shift the rear into the easiest gear then push the lever forward without pedaling to slacken the cable enough to then remove the casing from the frame stop. Andy