Local User and Radius User (Mixed mode of Authentication)

Hello Sharank.

No it's not possible: The BIG-IP system currently supports remote authentication through Active Directory or LDAP, RADIUS, and TACACS+. Using remote authentication methods allows the BIG-IP system to participate in a centrally located and managed access schema and use the password enforcement policies of the remote authentication server. However, if the remote authentication server experiences a failure, login attempts that use remotely authenticated system user accounts will fail, limiting access to system maintenance accounts that are locally authenticated.

The admin user is maintained through the Configuration utility, on the Users screen. The root user is maintained through the Configuration utility in the System menu, on the Platform screen.

For additional information: https://support.f5.com/csp/article/K12173

Regards