The Stop-RDSDBInstance cmdlet lets you stop the specified DB instance. After stopping the DB instance, AWS will not release metadata of the DB instance, such as the endpoint. The DB instance will still be associated with the allocated DB Parameter Group and DB Option Group. All the transaction logs will be retained for you to do the point-in-time recovery if required. Even if you stop the DB instance, you will be charged for the underlying resources used by that DB instance. Note that, you cannot stop or start a Multi-AZ or mirrored DB instance. You can only stop and start a single AZ instance. In this example, I have used the single AZ standalone DB instance WebSingleAZDB.
To stop the DB instance, you can use the following command:
PS C:\> Stop-RDSDBInstance -DBInstanceIdentifier "WebSingleAZDB" -DBSnapshotIdentifier "...