You can't actually do what your friend did. Banks aren't stupid. He couldn't pay the mortgage so the bank was realistic. He backed it up with a professional, an accountant, bank would have looked at the figures, in those particular circumstances they agreed, but only because it made sense to them. You can't make people pay who don't have the money and the bank doesn't want the property themselves.
In your case you don't want to pay because you prefer to pay for education costs. It makes perfect sense to you but it won't to a bank. Don't think about what you want, think about what the bank wants. So if I were you I'd be proving I couldn't afford the mortgages, same as your friend. How you do that, well you'll have to do your best on the figures and maybe just maybe you don't have your savings with the same bank so they don't know about them etc.