There is a more elegant method for blocking your webcam than sticking a piece of tape over it. And it won't leave a sticky residue behind should you later decide you'd like to use the cam. With the Device Manager in Windows, you can easily disable and enable your webcam.
Device Manager for the block
Open up the Device Manager by pressing the Windows key and the R key to open the Run dialog box and then type devmgmt.msc. Or you can just use the search box or ask Cortana to open Device Manager.
In the list of devices, look for a line for Cameras or Imaging devices. Click to expand that line and then right-click on the device, which will be called VGA WebCam, Integrated Camera, USB Camera or something similar. Next, right-click on the name of your camera and choose Disable device.
That's it! Your webcam is now out of commission. To bring it back, right-click it again in the Device Manager and choose Enable.