Determine where the groove needs to be made in the laminate floor. Measure and sketch out the lines where cuts will be made using chalk or a pencil--whichever will show up better against the floor color.
Set the blade of the circular saw to the depth of the laminate. Guard your eyes with protective goggles. Cut along each line using the circular saw.
Turn off the saw and set it aside. Remove the piece of laminate you have cut out and examine your groove. Use the edge of a utility knife blade to trim and smooth the groove borders, if necessary.