Turn off the furnace to stop the flow of air through the mobile home. This will prevent the ducts from emitting dust after removal of the vent that would otherwise have blocked it.
Remove any loose objects from the vicinity of the vent if it’s secured to the floor, to avoid having them fall into the ducting system through the open vent hole.
Examine the vent for any signs of screws holding it in place. If present, they will be on either side of the vent near the edges, with the screw heads flush against the vent surface. Look closely at the screws to determine the type of screwdriver needed for removal, either a flathead single edged blade, or the cross-bladed head of a Phillips-head screwdriver. If you see no signs of screws, then the vent is held in place by its weight alone.
Remove the screws holding the vent in place with the appropriate screwdriver, and set them aside for use if you need to replace the vent.
Put on the work gloves to protect your hands from the possibly sharp edges of the vent. Grab the vent at both ends and then pull it straight out from the hole.