I've just discovered you can remove the little red tag which appears above the Media button. Click on your username in the top right of the screen and select Preferences. If you look down the list which appears uncheck the one which starts "display unviewed media count". If you now click save at the bottom you may find, as I did, nothing happens and the preferences return to what they were. This I think was because I had not chosen a preference for alerts in chat which are right at the bottom of the page. This is shown as required but no selection had been made in my preferences, so I guess this was reading as an error. A preference I did change at the same time was to choose not to see signatures - for me this made posts much neater and easier to read!