角度更新和清除工厂变量

I'm creating a single page app in which a user searches for a term, the result gets saved in a variable, and a new page is routed that displays the result. I have this functionality working, however I want the variable to be cleared when the user returns to the previous page and most importantly when the user logs out. What's the proper way to do this? I want the factory to save things for certain pages that I want, and clear them for certain pages I don't want like "home" or "logout".I'm creating a single page app in which a user