Fix Burn-in

Adjust brightness settings. Try turning down the brightness and contrast on your TV and watch some varied content; it might go away on its own.
Enable Pixel-Shift. Many modern TVs have a built-in pixel-shift, or screen shift, which constantly moves the image slightly to vary pixel usage. If not enabled automatically, you should be able to turn it on in the settings menu. Other settings offer “Refresh” functions that can be manually run to try and clean out any image retention problems.
Play a colorful video. Running a fast-moving video with lots of color changes for a few minutes to half an hour may help if the above options don't work.
Get a replacement TV. Check your warranty to see if you’re covered for a replacement. If you're not, you'll have to fork over the dough for a new set on your own.

Although most PC monitors are made to be less susceptible to burn-in, it can still happen. If you run into it there are a few things you can try.

Turn off Display. Try turning off your display for at least a few hours, or as many as 48, ideally.
Use a White Screensaver. Try setting your screensaver to a pure white image and leaving it to run for a few hours. That may not remove image retention entirely, but it should dampen how noticeable it is.
Try JScreenFix. Some have also found success using JScreenFix. Although designed to fix stuck pixels rather than burn-in, it may help clear up any issues you’re experiencing.

How to Fix Screen Burn on Any Screen