Removing paint from brick walls can be tricky because of the textured surface. For thick, multiple layers of paint, our first option would be the Peelaway removal system. We recommend trying the PeelAway 1 and 7 Sample Twin Pack first to find out which product is the most effective on your paint type.You could try a small test area using a conventional paint stripper such as Paint Panther, paint and varnish remover then rinsing off the treated area with a jet washer. It's worth noting that the pressure shouldn't be too high as to splash the stripper over other areas and plants. care should also be taken not to wash out any loose render between the bricks.