The easiest thing to do is to remove them from the collection. If you want to have ads in a collection to appear while users swipe through articles but don't want the ads to appear in the browse page, try this:
1. Create a card called "Ad Card." Make that card wider than the layout you're using. If you have a 6-column layout, make the card 7 columns.
2. In the layout, create a card mapping rule called "Ad Card Rule" with Content Type set to Articles and Advertisement Type set to Ads.
Your ads won't appear in the browse page because they're assigned to cards that are wider than the layout.
[UPDATE] - I forgot about the "Hide from Browse Page" option. Much easier!