Hi, if the hoses are that hardened it isn't likely you'll be able to remove them without cracking or damaging them. Even if you can wrangle them off they probably won't fit tightly again as they have lost their elasticity. You'll probably find that they need to be replaced.
They are usually a real pain to replace though, because of access and leverage problems. Note that aftermarket hoses are generally very poorly made (they are mold-cast rubber), particularly the one that goes to the head, which will definitely increase the difficulty putting it on. Get well made hoses from the dealer, it won't cost that much more and use lots of silicone to help them slide on. Last, there is a plastic nipple that facilitates the attachment of the other hose to the rubber boot that the throttle is mounted to. If that boot is hardened loike the hoses there's a risk it could crack as well when you try to remove or install the nipple.