How do I cancel my paid subscription?
Go to your team's profile and billing page. Scroll down to the Billing section and click the button "Manage billing", which will take you to the payment centre. Click the button "Cancel plan". You'll be able to keep using your paid plan until the end of your current billing section, at which time you'll be downgraded back to the free plan.
The free plan has a number of restrictions, so your team may not be able to use Changemap in the same way — for example, only a single map is allowed. If you have more than one map active when your subscription ends, those extra maps will be deactivated, and you'll need to upgrade again to reactivate them.