Disabling Run Command From Start Button

1. Open Registry Editor. This can be done by clicking on Start button, selecting Run, inputting regedit and clicking on OK button.
2. Go to HKEY_CURRENT_USER/Software/Microsoft/Windows/Current Version/Policies/Explorer.
3. Right click on the pane on right and create a new String Value. Rename it to NoRun and put its value to 1.
4. Go to Task Manager.
5. End the process named Explorer.exe under the Processes tab.
6. Under Applications tab, select new process and type Explorer.exe in the dialog box that appears and click on OK.
7. Your Run in start menu or New Task in task manager button has been disabled.
8. To enable Run again, change the value of NoRun to 0 and restart the computer (since  New Task option will be disabled).