How to get rid of title bar in KDE to maximize screen real estate?

1. Use you favorite text editor to edit the file
   

   ~/.kde4/share/config/kwinrc

   In some distributions the .kde4 directory is called .kde (or something else like .kdemod4)

2. Add the line
   

   BorderlessMaximizedWindows=true

   under the section [Windows]
   It should look something like this:

   [Windows]
ActiveMouseScreen=true
BorderlessMaximizedWindows=true


3. Launch KRunner (Alt+F2) and run the command
   

   kwin --replace

   to restart KWin

4. Go crazy and maximize every window in sight! Remember that you can unmaximize them from the window menu (Alt+F3) or from the task manager in your panel. If quick tiling is enabled (System Settings → Desktop → Screen Edges → Window Management), you can also use Alt+Left mouse button to unmaximize windows by dragging them

This is a suggestion copied from here.