Bind off 7 sts at each armhole edge once, then 7 sts once. I understand the first "bind off 7 sts" but am confused about the 2nd one (7 sts once).
From the armhole side begin a bind off row and bind off 7 of them. Then work back across, then bind off 7 stitches once again, that will be all of them since you only had 14.
But here is what I would do: Bind off the first 7, then work back until 2 stitches remain, work those last 2 together. Turn to begin the new row, and bind off 6. This will tame the stair step effect you get on this type of bind off for shoulders.