Find the edge of the finished flooring in the room. This edge will have the groove side toward the wall, not the tongue side. If necessary, use a pry bar to pry off the quarter-rounds or baseboard on top of the flooring to find the edges.
Remove any adhesive on the side edge with a heat gun. Past installation methods for Pergo flooring included gluing down the side of the last row. Hold a heat gun over the wood and move it back and forth to melt the glue. Do not hold the gun in one position too long and do not hold it too close to the wood. Once the adhesive starts to loosen, pull it up in a strip.
Disassemble the flooring. Pergo flooring is click and lock, meaning the tongue side fits into the groove side of the next board. Pull the board toward you and lever it upward to release the tongue from the groove.
Remove any adhesive underneath the planks. If your Pergo flooring was glued down, you'll need to loosen each board from the adhesive. Run the heat gun over each board until you can wiggle it free. Once the board is free, melt off any remaining adhesive left on the back.
Sort through the planks. Discard any damaged boards and stack the remaining planks together away from heat and light until you are ready to re-use them in another room.