It sounds like this hat is being knit flat, i.e. back and forth, not in the round. Cast off 7 sts at the baginning of the row and work to the end of the row. Then turn, cast off 7 sts and work to the end of that row and repeat this 10 times in total (so 7sts in each row for 10rows). You're gradually shortening the length of the rows you will be knitting until there should be 7 sts remaining and then you cast them off (cast off the last 7sts).
Wow, congrats on completing so many projects in the first month!