I recently replaced my straight handlebars with trekking bars and now want to shorten the first section of cable housing a bit on my brakes and derrailleurs.

I disconnected the front brakes this weekend and was all ready with my (new) cable cutters to tackle the job. I thought I would simply take out the inner cable, slide off a ferrule from the cable housing, cut the housing a bit, put the ferrule back on and re-insert the inner cable. But I was stymied. I cannot figure out how to remove the ferrule from the cable housing. It wouldn't simply pull off. I tried pulling the ferrule off with pliers, but didn't apply too much pressure because I was afraid of damaging the cable housing. Still couldn't get it to budge.

Any thoughts? Are the ferrules not removable? Should I use more pressure with the pliers? Should I just cut that section of the housing off and use new ferrules?