If you haven't done so, read the "Caution" thread in this forum. If there's still any refrigerant in your system, removing the hose would be dangerous. (I'm assuming you're new to A/C stuff because of this question.)
So, once you are sure that your A/C system is empty and you have your goggles on anyway...
There are a couple different kinds of A/C fittings on an A/C system-- I assume you are talking about the spring-lock type since it's obvious how to remove the others. To disconnect these, you need to remove the safety clip and then use a spring-lock disconnect tool (available cheaply at any parts place and also known as a fuel line disconnect tool). You slide the spring-lock tool into the fitting to expand the o-shaped spring and then pull the fitting apart.
EDIT:
After replacing the hose, you'll need to evacuate the system with a vacuum pump and then recharge with the proper amount of refrigerant. Let any oil trapped in the hose run out and measure it so you can replace it with an equal amount of new PAG oil. Tape or otherwise seal off the openings after you remove the hose if you are going to take any time to put the new one on-- that will prevent excessive moisture from getting into the system.
Read up on the sticky posts before you do this stuff to learn how to do it right.
