How to remove dried on grout off the top of tile?

Use warm water and wipe it over the surface of the tile with a sponge. Take a some fine wire wool and gently rub over the grout. It should begin to dissolve and rub off at the same time. Once the grout has gone wipe over the tile with a damp cloth and let dry

It should pop right off try something plastic and firm to get under it

If tile is porous there are some really great nano based grout and mastic removal products at big box stores. I used one to clean off stone tile backsplash and it worked well with some scrubbing. Sorry, cannot remember the product name, it is in a grey bottle...