After I upgraded my mac to El Captitan, I found that there are some of apps like Google Search and Youtube, which I didn't installed by myself. Actually those are Chrome Apps, like Google Music app.
What is Google doing? I don't understand why they install these apps and showing them in application lists. I decided to remove them because I never use them.
Go to Your Home --> Applications --> Chrome Apps and you will see the apps. Just move the apps you want to remove to trash by 'Command + Delete'