I am using ZkBasicAuthAccessControlFactory for authentication. Is there a way we can change the default admin password for this?

I think you can check : https://github.com/apache/pinot/blob/d4cb93dbda1e268e0c064b1b3c62e8b81599db32/pino[…]r/src/main/java/org/apache/pinot/controller/ControllerConf.java