Remove from the line up is done by moving the cursor just above or beside the page tile until a hand icon appears then shift-click-hold and flick up and off the top of the webpage.
Another way to remove pages in the lineup is to double click on a title Favicon and all pages will disappear except that one and the Welcome Page.
Clicking on the web browsers back arrow or back button will replace the lineup as it was.
Remove from the site is a little trickier. See