Disable Default System Accounts

Girishf5,

check out support article K52286304 to identify the default system accounts, and then check K15632 and/or K14943 for detailed instructions how to disable/remove them.

BIG-IP system administrative accounts

https://support.f5.com/csp/article/K52286304

Disabling the admin and root accounts using the Configuration utility or tmsh

https://support.f5.com/csp/article/K15632

Removing the default BIG-IP administrative user

https://support.f5.com/csp/article/K14943

Cheers, Kai