Cancel the billing agreement of the active suite license, wait for it to terminate at the end of its paid period, and then purchase the desired suite license on the access license purchase form.
The billing agreement is cancelled by using My Account, Manage Access Licenses in the menu, clicking the black hamburger menu of the relevant access license, and then using the Cancel Billing Agreement menu option.
Once you've purchased the new suite license, you need to move everything that was connected to the old license to the new license.