You can manage your premium account anytime by navigating to the hamburger menu beside your avatar (in the upper right corner), and then clicking billing.
On the billing page, find the box labeled "My charges" and toggle the button from premium to free.
After toggling to free, you'll see a popup asking you to confirm your choice. Click the downgrade button on the popup to save your changes.
You'll also see that the button under "My charges" has been toggled to free, along with a count of any remaining days left on your premium subscription.
You can upgrade back to a premium subscription anytime to enjoy the benefits of unlimited job posts, unlimited candidate search and unlimited chat. Learn about the difference between monthly and annual subscriptions here.