To place your account on hold, you simply need to remove the credit card on file. When you are ready to restart, you can just reapply your credit card again.
Your Volunteer Organization's page will become dormant and no one will be able to make changes. Though all current information will remain, you won't lose anything. People who add hours during the time the account is on hold will be placed in an approval queue to be approved after a new credit card is applied.
To put your subscription on hold for any period of time you can go to the Organizer Dashboard
In the top right corner, go to Payments, then under "Cancel Plan" click on Cancel