Just right click on entries for "Delete this Page" or "Forget this Site"(for a string of entries). This is for Win. I presume it is similar for Mac.

thanks, worked like a charm. and of course it was simple :D

Is this in the popup that appears when your typing a web address? If so it doesn't work for me.

at first i tried ctrl-clicking in the browser as it appeared whilst typing, which only took me to the page itself; then i realized i should have been in the history tab, repeated the function in there and it worked.

You can do a search in the Library (History > Show All History) or History sidebar for each website and select all pages with Ctrl+A and delete them via the right-click context menu or with the Delete key.