Maintenance window required for remediation? Maybe. Decreasing the policies to reduce usage may require a maintenance window. Increasing the minimum threshold values for entities do not require a maintenance window.
Resolution: This Alarm is automatically resolved once the the number of objects of the specified type defined comes down or minimum capacity threshold has been increased. Navigate to the capacity page under the NSX overview UI of respective feature (i.e. Networking, Security, Inventory and System) and review current usage versus threshold limits. If the current usage is expected, consider increasing the minimum threshold value. If the current usage is unexpected, review the network policies configured to decrease usage at or below the minimum threshold.