You can promote a Read Replica via AWS CLI or AWS Web Console.
Reference:
- https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/USER_ReadRepl.html#USER_ReadRepl.Promote - https://awscli.amazonaws.com/v2/documentation/api/latest/reference/rds/promote-read-replica.html
aws rds promote-read-replica \> --db-instance-identifier test-instance-repl>>
Best regards,
Dan Smith