If you're decreasing the number of user licenses on your Insightly subscription plan, you may need to remove active users from the account before proceeding. For example, you can't select a three-license subscription if there are four active users on your account.
First, one of your Insightly administrators will need to go to the System Settings > Users page to delete the active users who won't be using Insightly. After the excess active users are deleted, you can go to the Billing & Account pages to reduce the number of licenses.
Now, when changing the number of user licenses on the subscription page, you can select the number of licenses that matches the number of active users.