I've been looking in the settings all the time but can't find anything
Clean up browser
Sign out of Gmail on your own computer;
Open your Gmail. Click on your photo in the top right corner. Click on Unsubscribe.
Click on your profile picture in the top right corner and select Log out / Log out.
Go to http://www.google.de/....google.de and then click on the profile picture in the top right corner and then on "Log out"
If you can't find anything else, you can also register via YouTube