If you see something similar to this:
This is a fake message and your computer is not infected. The message is a common scam which is trying to scare you into calling the displayed phone number so the scammers can get access to your computer.
The pop up can be difficult to close. You can just restart your computer or close your browser through Task Manager.
To close this through Task Manager:
1. Right-click on the time/date in the bottom-right of your screen, then click Task Manager.
2. Find your web browser on the list, right-click it, then click End Task.
*If you don't see your web browser on the list, you may need to click 'More Details'.
3. You can now re-open your web browser and the message should be gone. You may get a prompt to 'Restore Pages'. Do not choose this option. Simply close the box with the 'X' and continue using your browser.