Photos please. And then list the grout you used. Normally grout MUST be cleaned off at the time of install. Once it hardens it is SUPER TOUGH to get rid of it. That's why professional tile setters make every effort, at the end of each day, to clean up their work. It prevents them from having to work their butts off on the last day (or last three days if they were super lazy).

Who laid the floor?

Get some salframic crystals from your tile store...or possibly from Home Depot. Mix as per the instructions and srcub the tile....wash with clean water.

This is the grout we used. You can see in the picture that there is still the grout left on the flooring.

Ok...so let me get this straight. You laid a VINYL tile floor and added VINYL TILE GROUT to the seams (to give it that realistic look). You were unable to clean the grout haze off of the tiles and now, several weeks later, you are looking for a fix to the haze?

The vinyl tiles and vinyl grout products are different (in chemistry and in use) than a 'regular' grout. You will want to reach out to the manufacturer of BOTH products (tile and grout) to find out what can and CANNOT be used to deal with this issue.\

For each chemical (like the vinyl tile grout) there is an 'undo it' chemical. The tricky part is when the 'undo' product is NASTIER than the first chemical. In other words, the cure may be worse than the disease.

Please reach out to TEC and ask about a stripping chemical. Then reach out to the vinyl tile manufacturer and ask if that chemical is allowed over their tile. Go from there.