Enabling, disabling camera from terminal

Press Ctrl+Alt+T on your keyboard to open the terminal.

When it opens, run command to disable the camera until reboot:

sudo modprobe -r uvcvideo

You will be asked for your password, and after typing it, if there are no errors shown in the terminal, your webcam should be disabled.

To enable your webcam again, run:

sudo modprobe uvcvideo