If you have to cut the water off going to the washer to stop the water the water valve is bad and needs replacing.
If turning the washer off stops the water flow the problem is either the water level control or the tube that runs from the control to the tub is stopped up. Most likely the tube is stopped up. Remove the front then look at the bottom left of the tub. You should see a box with the tube connected to it remove it. Often this tube will stop up right at the end and you can clean it out with a toothpick. Hope this helps!