The reason behind selling the project is that our team decided to split up and angel investors need their money back. Nobody does marketing now and I began to work on other initiatives.

You don't have an investor, you have a creditor (might I say: a loanshark). Investing means there's risk of not getting your money back, loaning means you get your money back no matter what.

learning the hard way :)

You liquidate the company, and the investors get what they get. They're not going to get their money back. I'd be blown away if you got a few thousand for it.