Then you can wet the wallpaper.

For washing wallpapers, you will need a spiked roller. They need to roll on the wallpaper so that the thorns are pierced by a waterproof coating. Then you can wet the wallpaper. To steam the wallpaper, you can use the old sheet that needs to be wetted in hot water and attach to the wall that needs to be cleaned. With an iron until completely dry you need to iron the sheet. After that, you can easily tear off the spatula.