@Sai Kiran Maturi Thanks for reaching out to Microsoft Q&A, apologize for the inconvenience caused on this.
Automatic backup will get enabled automatically after the creation of web app unfortunately you cannot disable or download the backup files of the automatic backup and all the backup files of automatic backup will be stored in backend.
Your feedback is noted, and I have relayed the feedback internally to our product engineering team.
I would suggest you to raise a feedback item on this using Uservoice here - All of the feedback, you share in these forums will be monitored and reviewed by the Microsoft engineering teams responsible for building.
Feel free to reach back to me if you have any further questions on this.