You should, but you don’t have to. Before most flooring installations you’ll want to remove existing flooring in order to get a clean, flat, dry subfloor. This is crucial for nail-down and glue-down installations and may involve pulling up old carpeting, tile, or existing floorboards. If you’re floating new flooring (without any nails or glue) you may do so over existing floors as long as your foundation is clean, flat, and dry.