Bricks, Masonry, Asphalt and Concrete - can you scrape concrete?

Is there a way to scrape layers of concrete? I am looking to try to even out, or level, two pieces of concrete that come together to get water to flow away from a garage. I need to srape down a section about 6 inches wide and 18 feet long. Right now, the garage floor and driveway come together at a high point and the water is not flowing away from my garage, but is flowing back inside under the garage door when it rains due to the concrete meeting at a high point. I am looking for a solution on how to get the concrete to flow away from my garage without pouring a whole new garage floor. Other ideas have been cutting a channel in the concrete and putting a metal grate over it, putting a drain on the inside corner of the garage where the water is coming in by, and/or mudjacking the garage floor so it is flowing the right way. Anyone else have ideas?

I would vote for the trench drain in front of the garage. You can scrape concrete. The machine is called a scarifier. It will grind away the surface but will leave a rough surface on which you can see all of the aggregate.

Pecos