Well, played around with the default theme, and figured out how to remove the title bar. If others want to remove the titlebar from the window also, then here is how.
1: Open /usr/share/themes/Adwaita/metacity-1/metacity-theme-3.xml
2: Locate the element <frame_geometry name="max"
3: Set "has_title" to false
4: All the sub <distance elements should have the value "0" and the <border elements should have top and bottom set at "0", otherwise a tiny part of the title bar remains.
When doing this, remember that your close button is gone when maximized. But, gnome shell already includes a close option in the panel for focused windows.
Now, if anyone knows how to fix the global menu to make it work with gnome shell, please let me know.