Everyone should own a seam ripper. If you sew at all, you already are quite familiar with this little item. A multitude of errors can be undone with a seam ripper.
But even if you can barely sew on a button, you really should have a seam ripper in your stash of odds and ends. They cost about a dollar and can whisk off an icky Target tag in no time.
Just stick the pointy end under one of the stitches until it slices the stitch in half. Work your way down the seam or stitch line. Before you know it that cheapy tag is gone and you haven't harmed your garment at all.