I played a game where the enemy placed wards at creep camp. It really messed up the game as I can't pull the creep close to the outer towers. If I pull the creep from camp closer to the inner tower, I'm leaving the other lani
Well, obviously you need to destroy the observer ward inside/near the camp. In order to do that, you need True Sight, i.e. the ability to see invisible units (and Observer Wards). Beware that since wards are immune to debuffs, a simple Dust of Appearance will not suffice. You will either need a well-placed Sentry Ward or a Gem of True Sight to deward. Of course, since the need to deward is mostly felt in the early game, you as a support will most likely not have enough gold to buy a Gem.
The most important thing to be aware of is then the fact that even after dewarding your own Sentry Ward might be blocking the camp by itself. However, Sentries only last 3 minutes, while Observer wards last 6 minutes, so if you deward early enough it might be worth it even if you mess it up. Anyway, when you actually deward, bring the flying courier to you because you might need the flying vision to spot the enemy Observer ward if it's hidden amidst the trees.