I find that as soon as I click on the bell icon, it presents a list. I don't have to do anything to clear it after that. In other words, I don't have to open any of them. I just have to click on the bell icon, and then click anywhere else on the page and it clears of notifications on its own. But if you're trying to find a way to have them never show up to begin with, I'll leave that solution up to the admins.
The other option is to simply ignore it completely as you don't want to be notified, which means you don't plan on actually checking to see if there are any that are of interest to you. Mine tend to build up, but I'll occasionally check to see if any that I'm intrigued by.