How to get rid of my CTO?

A friend of mine and I have been working on this project for a while now (3+ months), he built the roots of the product but he now can't work on it anymore because he has a job at a big bank. He offered to reevaluate the share of the projects to 90/10 instead of 50/50, basically giving away 40% of his shares to me.

The situation is that our product is only at the prototype stage and we still haven't found any accelerator/investment and are still some time ahead of being able to. I'd like to retain the full 100% of the project and avoid leaving him with 10 he asked, this is because I don't think it makes sense for me to go to an investor and tell him that 10% is already gone to some guy who doesn't even contribute anymore. I also want to maximise my chances of finding people interested in working with me on the thing. So I'm basically trying to buy him out, but the offer he made me (3000£) is way above what I think a half finished product with high statistical risk of failure is actually worth it.

Any ideas? Anyone experienced something similar?