There is no need to close your position if you'll need someone in the next few months. You can simply update your calendar, block the dates when you don't need volunteers and plan ahead. This way you'll always have someone ready to help you out.
If you do not know when you'll need another worldpacker, go to Volunteer Positions -> Close Position.
You can reopen it whenever you want, just follow the same steps and click on "reopen position".