Hello all,
Having made the mistake to not clean the surrounding areas properly after applying grout on the outdoor tiles, it's left with a big regret that I should have rubbed it off with sponge a couple of more times not just once. I assumed they could be washed off later easily.
I have tried kitchen metal scrubber, gif and sand paper all of which made a small difference but still a long way to go. Besides the sand paper is changing the surface of my tiles from rough to soft being the most effective method 😐.

What else can I use?