Taking off the "beauty ring" from around the vent hose on the interior wall and the vent cap from the exterior wall to begin the removal of dryer vent hose. Removing the sealant around the hose may be necessary to dislodge and free it before putting the new hose in.
Unplug the dryer, and slide it away from the wall and vent. Unhook the hose to the dryer from the wall. Remove any screws holding the plastic cover, slide the cover off, and look inside for spray foam insulation or caulk. Use a utility knife to cut away any sealant and loosen the hose.
Go outside to the exterior vent, and remove the cap. This may require a screwdriver or drill to remove fasteners. Use a jab saw to cut any spray foam insulation loose so that the hose comes out. If the saw doesn't work, use tin snips to cut the hose, use pliers to grab the vent on either side of the cut, and pull the vent from the insulation until it comes free.
Grab the vent again, and pull the vent from the wall. Slide the replacement hose into the hole in the exterior wall, and attach the vent hood. Apply a new bead of caulk around the vent hood to prevent moisture from entering the house. Spray some foam insulation into any gaps between the inside wall and the new vent hose. Go back inside, and repeat the insulation process. Replace the "beauty ring," and attach it to the wall. Connect the hose from the dryer to the wall vent, and plug the dryer in.