It is very easy just to close tabs on a browser when you are finished using a website, however this means the website you are using, may still keep you logged in, and on a shared computer someone may access your data.
it is so easy to close websites, and it should be a routine operation.
Look for your name, or your picture or a ‘log out’ type button, click on it and choose the option to sign out or log off.
the video below shows how simple it is in the first instant to simply close a tab, but then the user goes back and completes the sign out process, in just a few seconds.