Billing Because of RDS Backup Services

RDS Backup services can be disabled by going into the RDS console and selecting Modify. Then identifying the location where automated backups are enabled. Change the setting to 0 and this will disable the automated backups. To disable automated backups immediately Sign in to the AWS Management Console and open the Amazon RDS console at https://console.aws.amazon.com/rds/.

In the navigation pane, choose Databases, and then choose the DB instance or Multi-AZ DB cluster that you want to modify.

Choose Modify.

For Backup retention period, choose 0 days.

Choose Continue.

Choose Apply immediately.

Choose Modify DB instance or Modify cluster to save your changes and disable automated backups.

Detailed link provided below: https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/USER_WorkingWithAutomatedBackups.html