Removing dried-on grout is possible, but requires quite a bit of effort. When installing new tiles, make sure to clean up the grout as well as possible before it has a chance to fully set. It can take many days for grout to fully cure, so there is plenty of time to wipe it away before it has become fully hardened.
How do you remove grout without damaging tile?
https://www.youtube.com/watch?v=A_CEJv5crHM
How do you remove stubborn grout residue?
https://www.youtube.com/watch?v=fDOFDCaSAtI
What is the best tool to use to remove grout?
- An oscillating tool equipped with a grout removal blade is one of the best options, and with the right blade, can be used on any type of grout. ...
- A reciprocating saw with a grout grabber blade is ideal for removing hard grout, like sanded or epoxy varieties.