Depends on your clearance and what you can shove in there. If the hose is old, be very gentle with it, and tubes they connect to so you dont break anything.
A lot of times Ill grab a pair of channel locks and where the hose overlays on the tube, I will grab and gently twist back and fourth while pulling on the hose at the same time. Just pulling on it doesnt do much because you have to break the deposit build up that is bonding the hose to your tubes.
Also, you can try to take the pliers and grab the hose where the metal tube ends, and squeeze the hose at that point. It will put pressure on the hose to slip off the tube.
If you can get a little pick or probe inbetween the hose and tube, try to see if you can loosen anything up in there.
Twisting motions have been most successful for me. Twisting and a pull to either side at 90* to ease it off. The pulling force doesnt give you enough pull and you could pull your tubes out of your heater box before the hose slips off.