How to remove a blur out of a picture that someone intentionally included?

No sorry. You would need the orginal photo. Once the blur is in place and saved a jpg there is no way to unblur it. Ask him if he still has the orginal.

You can't, but people seem to think that you can. The rule for photography is to capture the cleanest, most balanced and highest resolution you can possibly capture. Then you degrade them in photoshop and add blurs, that sort. You can't really add more pixel info, just take it away. Now you could clone stamp and remove some of the blur yes. And maybe you would never know, but it would be a lot of hours and very expensive. And you would need a clean shot to sample from. So if you have a series of pics and one is blurry you can sample the clean shots into the blurry one and reconstruct it pixel by pixel. Which is the reality of photo restoration.

the only way is if it's an adobe photoshop .PSD file with the original file data, or if it was saved as a TIFF file with layers, and one of those layers happen to be the original unblurred image. If the blurred picture is a JPG, there's nothing you can do.

Copy your face out of another photo and Photoshop it into the photo in question, only way without having access to the original.