How to Logout of YouTube on Android

Head to Settings and select the tab "Apps". Find the YouTube app and select it; you should then see some information about the app. Click on Storage, Clear Cache, and finally Delete Data. Your phone will now ask you if you really want to do that, just click Yes. Now close Settings and go back to the YouTube app. Click on the little image on the top right of the page. You should now be on a page called Account. There, click on your name on the top of the page and wait for it to load. You will now finally find the Sign Out option. Just click it and you're good to go!

Go to Google Play, search for YouTube, click "Uninstall". It'll revert back to the old version of YouTube, and you can sign out of your account.