Before you can begin removing the mail slot, identify what size and kind of screwdriver you require for the task. Mail slots are typically held into position with four screws on each face plate. Check the heads of these screws and obtain the correct screwdriver for the job.
Remove the four screws in the exterior plate, which allows you to lift the plate off the door. Repeat the process on the interior plate to remove it. Although some mail slots vary in design, the majority adhere to the door with screws.
Although you must cover the opening in the door, it's ideal to first insulate the gap to avoid cold air blowing into your home. Insulate this area with one of two styles of insulation. If you have batten fiberglass insulation, pull off several large pieces and stuff them into the gap in the door. Alternatively, cut a piece of fiberglass board to the correct size and place it in the gap.
Covering the gap vacated by the mail slot completes the job of removing the mail slot. Covers for this task are available at home improvement stores, especially those that sell items such as mail slots. Covers are sold in colors such as gold and silver to match with your door hardware. Install the cover on each side of the hole in the door by screwing it into position with its mounting screws. You can also add some sealant around the outside of the door to protect against moisture. Installing this cover is an effective way to protect your home from intruders, too.