Depends on if there's any bias. If not, I use the Ricky Tims caveman method. If there's bias then I do the more careful cut a top stitch here and there and pull out the bobbin thread.
I've also been known to take my seam ripper and insert it in the seam with the ball side of the seam ripper against the underside of the fabric with the pointy end on top where you can see it and slice all the way down the seam. This works pretty well and as long as you make sure the ball side is against the fabric you won't cut the fabric, but it's not as fast as the Ricky Tims method.
Rob