Cancel Scheduled Maintenance for AWS RDS

To change the maintenance window to a preferred time, see Adjusting the preferred DB instance maintenance window.

Changing the maintenance window for an RDS instance doesn’t require any downtime. However, if there are one or more pending actions that cause downtime, and the maintenance window is changed to include the current time, then the pending actions are applied immediately, resulting in downtime.

To postpone a maintenance action that's scheduled for the next maintenance window, consider changing the maintenance window of your DB instance to the next feasible window.

Important: Changing the maintenance window continuously to avoid downtime might lead to the maintenance actions being applied at the time of highest usage. This might cause an outage.

Reference - https://repost.aws/knowledge-center/rds-maintenance-window