Many-many thanks, it worked like charm.
Our users don't have physical access to systems.
All icons are excluded from wBar, except 'Exit' and 'Remote Desktop Connection'. The mouse click-context-menu is also disabled. Now 'TC Exit option' is modified. I think there are only remaining possibilities to access 'terminal' or TTY is using 'CTL+ALT+Backspace' and 'CTL+ALT+F1'.
I am not familiar with window manager, I will explore it.
Thanks for your comments.