I don't think you can, which basically sucks. That's a new thing we will hopefully have in Fm14. But if i'm not mistaken after the season is over the board will probably take those 20mil to clear the debt.
Unfortunately not... Debt just goes out in monthly payments until it is paid off... It's a pain because I had a bank balance of over 100 million at villareal and they still didn't pay off the debt in one chunk meaning I couldn't get a new stadium