Automatic backup creation and deletion weekly in F5 device

There's so many ways to do this. Without reinventing the wheel, I can quickly share you the reference links where F5 enthusiasts have already shared codes and methods/scripts to achieve this.

BIGIP (LTM/GTM) Automated Backup

Configuration Backup Scheduler

F5 Automated Backups - The Right Way

Third Time's the Charm: BIG-IP Backups Simplified with iCall