I modified the crown of this hat so that it can be worn as either a regular slouchy beanie or as a ponytail hat by closing or opening the drawstring at the top of the hat. I followed the pattern through round 9 of the Decrease Section, omitting round 8. I then finished as follows:

Rounds 10-12: knit.
Round 13: k4, yo, k2tog, k to last 5 sts, k2tog, yo, k3.
Rounds 14-16: knit.
Round 17: knit each stitch together with the purl bump from the corresponding stitch from round 9 (4 rows below the eyelet row) and bind off. (You could also BO and then fold and seam.)

I made a 3 stitch i-cord long enough to feed through the hem and tie in a bow and inserted the i-cord into one eyelet of the hem, around the crown opening, and back out the other eyelet. I made 2 pom poms and attached to the ends of the i-cord.

If I were to make these modifications again I would add an additional 2 rows of stockinette before and after the eyelet row so that the i-cord fits a little less snugly inside the hem (or use a different type of cord that is thinner). I would also place the eyelets closer together.