Brush the paint stripper gel onto the stone pavers using a three-inch natural bristle paintbrush. Apply an even coating of the gel, covering the entire surface of the pavers, as well as along the sides of the pavers where the polyurethane sealant may have seeped.
Cover the stripper-covered pavers with a damp bed sheet to keep the stripper from drying out as it works on the tough polyurethane coating. Allow the stripper to sit on the paver surface for the amount of time suggested by the stripper manufacturer.
Remove the bed sheet by pressing firmly on the sheet's surface as you scrub off the sealant along with the stripper gel.
Wash off the stripped pavers with a water hose to remove any of the paint stripper residue. Wait an hour for the pavers to dry and then inspect the paver surface to determine if any sealant remains.
Repeat the removal process if the stripper application fails to remove all traces of the sealant. Use a fresh damp bed sheet with each application to prevent transferring already removed sealant from the used sheet to the pavers.