Scrape off loose dried grout with a plastic putty knife or nylon scraper
Dampen the grout with warm water and let it sit for a few minutes
Apply a grout haze remover or a diluted vinegar solution if the tile is acid-safe
Scrub the grout with a nylon scrub pad or stiff nylon brush
Use a razor scraper carefully on ceramic or porcelain tile only
Repeat soaking and scraping until the grout softens and lifts
Wipe the tile clean with a damp microfiber cloth
Rinse the area with clean water
Dry the tile with a clean towel
Test any cleaner on a small hidden area first
Avoid metal tools on delicate tile surfaces
Wear gloves and eye protection when using cleaners