Examine the surface of the mirror to determine if brackets are visible. If brackets are present, remove the screws using a screwdriver and lower the mirror to the floor. If no brackets exist, grasp the sides of the mirror, and lift it up to detach it from the mounting nails or brackets on the back of the mirror.
Spread a towel or a blanket on a table and place the mirror on it face down. Pry up any metal tabs that hold the mirror in place using the tip of a slotted screwdriver. Lift the mirror up to determine if it detaches from the frame. If it does not detach, proceed with further removal steps.
Turn the mirror face up on towel and place another towel on top of the mirrored portion to protect it from damage.
Slide a slotted screwdriver or a putty knife under the edge of the frame and twist it gently to detach the frame from the mirror. Continue working your way all the way around the mirror frame until the entire thing detaches. In some cases, each side of the frame may detach separately.