bathtub drain stuck

My bathtub drain is stuck, and I used lots of Drano Clog Remover in the past, but it only lasted for a few days. Also I tried all kinds of Drain Clog Remover Cleaning Tool, and none of them works.

Currently, I want to completely remove the existing bathtub stopper, and install a drain cap that looks like

However the current drain looks like

and it looks like there is a metal rob stick out of the drain, and i can't remove it. has anybody had similar issues in the past? thanks for any help.