Learn how to kill a specific process in the Windows operating system

Step 1: Click the Close button.
Step 2: If doing so, does not work, start the Task Manager (Click the Start menu, click 'Run...', type 'taskmgr', and click OK, or use the shortcuts Ctrl+Shift+Esc and Ctrl+Alt+Del), select the task that you want to close.
Step 3: If even that does not work, right-click the task you want to close, choose 'Go To Process', and note the process name of the task. Start the Command Prompt (Click the Start menu, click 'Run...', type 'cmd', and click OK), and type the command
 taskkill /f /im "process_name.extension"
, replacing "process_name.extension" with the process name you earlier noted, enclosed in double quotes.
If even that does not work, the only way left is to reboot the system, but before doing so, make sure that the task is not in the startup.

Here is a video to explain how it is done:
Link