This is the internet.
It's where everything that everyone loves and hates comes smashing together in a confused mound.
And generally speaking you just have to deal with the fact that it all exists here.
For example, I hate Warhammer 40k. Whenever I see an image of it I will simply ignore it, rather than complaining that it exists on my screen.
I don't like or dislike the pony images, but you just have to realize that nothing is truly stopping anyone from posting anything that you don't like. Unless the place you are at has a rule against it, you just have to ignore it somehow.