How to turn off details being displayed in Media Player Classic?
Go to Menu -> View -> Render Settings. Click on Display Statistics. Or Press Ctrl+J.
Note: You must do either of the steps 3 times to disable it.
I pressed a shortcut key and currently not able to turn this details off
Your image is showing the basic info of the media file being played.
You should be able to toggle this with ctrl2 or Menu → View → Information