Over at Stack Exchange, one intrepid user asks,
I would like to know if there is any way to block Facebook and other sites from being added to Safari’s Top Sites. Someone knows how to do that?
One answer is to completely keep new tabs or windows from showing Top Sites, but that’s not really the best answer. There is an answer, pulled directly from Apple’s own support page for Safari 6, however, that fits the bill.
Apple lists steps to customize the Top Sites page. In essence, all you need to do is open Safari, and then open a new window or tab, which should bring up the Top Sites page. You’ll see a bunch of square web page previews, showing which sites you go to often.
Click on the Edit button in the lower left of the Safari window, and then each web preview will get an X box and a pin icon in the upper left. If you want a certain page to never show up in Top Sites again, click on the X.
If, however, you want to keep a specific site in the Top Sites list, click on the pin. You can also display 24, 12, or 6 web previews with the Small, Medium, or Large buttons, respectively. If you want to move certain sites to specific locations on the Top Sites page, just click and drag them around.
When you’re finished? Hit the Done button (where the Edit button was) and you’re good to go.