Start cmd in windows and delete all the .mp4 files in a folder

Start cmd in windows and delete all the .mp4 files in a folder.
1.Search for cmd and you will see it like this.

2.Once you click on it,it will appear on its own window.

3.Lets say i have a mix of files in 'Documents' folder and i want to delete all the mp4 files. enter the command  del .\documents\*.mp4  ,use the full path if you are not sure from where you are executing your cmd.see bellow.