You could do it if you wanted to. The easiest way to do it is to either uninstall it or do a system restore to a date before your computer downloaded it.
Not really a good Idea. Most of the time it's just a sales trick as you are clicking on this and that you will find you will have to sign up for this or that and pay for it.
The fact that he may or may not have been gay shouldn't influence if or if not you should see one of the most beautiful paintings in the world.
If you get the chance to go see it don't worry about something like that.