Tile grout removal.

Hi, go around with a scraper first and gently remove any large bit of grout. Then a apply a grout remover or residue remover, we buy ours from Topps Tiles when correcting others work. Follow instructions on the bottle but use hot water and a scouting pad. Finally wash off and you should be sorted. You may need repeat this a couple of time to complete job fully

If it was Mapei grout Lithofin make an acid that will dissolve it, an emulsifying pad goggles and marigolds and open the windows for a through draft, better still call the messy sod back to do it for you FOC.

Yes,agreed about using scraper to remove bigger grout bits off,but if there are big bits of grout left so don't think it's a good tiler,if can't wash it off properly imagine what's behind the tile... Anyway,I use vinegar mixed with water,no too much vinegar as it smells,when that used to spray on tiles 2 to 3 times every 30-40min it removes most of it and don't need to use any sharp sponges or other things could cause any damage to the tile.

I would use a Stanley knife as scrapers can leave metal scars. Then use residue remover with a scotcbrite pad making sure you sheet the bath off first as the residue remover could stain the bath.