Click on “Unread”, to the upper-right there should be a button labelled “Dismiss…”.
Click that button, then click the Dismiss button in the window that pops up.
You probably don’t want to use the checkbox to stop following all the topics, but what do I know 
Oh. Thanks for telling me this, because it was bugging the crap out of me to have every page I don’t read be listed on the top of my feed.