Why would a 6-year-old dog all of a sudden start licking carpeting and fabric every chance he gets?
Your dog could be nervous or their could be changes to it's routine. If you are renovating your home or have been working longer hours this could put the dog off. These dogs need a lot of exercise and just being out in a backyard isn't always enough. Dogs love to for runs or walks with their owners and the dog could simply miss you. Spend more time with it. If the licking persists it could simply be the fact they like the feel of it, but I'd have a vet check the dog out.
You might try the method that works for the removal of wax from fabric. That is, using a warm iron over a paper towel to melt the crayon and absorb it into the paper towel. B: I added a link to the Related Links that has a rather lengthy description of the process to remove wax from fabric or carpeting in the car. It's worked pretty good for me in both cases.