You can delete your instance or change the plan it is on anytime via MyMalcolm.
To delete an instance visit the Settings section of MyMalcolm. You can also move between different types of plan in the Billing section of MyMalcolm. Remember that different plans have different quotas so you might need to reduce the number of FAQs you have (for example) if you are moving from a Team to a Micro plan.
You can cancel an Instance anytime although bear in mind that Micro and Team plans are billed monthly in advance and you won't get a refund for any unused portion of the month you have paid for when you cancel.
If you are on an Enterprise plan talk to your Account Manager for any changes or cancellation requests.