Just be a little easy on the wiper, you can damage things. If it really won't come off with the above, first try to break rust by hammerring it once, this might give slight damage but a hammer and screwdriver and a quick blow is what I recommend, or with some other tools that are more fit for this job but I wouldn't know what that is though and then some wd-40 and then wiggle it some more.
I wonder what you will use to cover the hole?
