That doesn’t make money disappear. Governments levy taxes and issue bonds to have money that they spend. They could just disappear money, but they don’t, because there’s always something to spend on.

The government could issue bonds to cover all the outstanding student debt. It’s not cancellation, it’s shifting the debt. The government could then do whatever they want with it, but it’s money they’ve spent that has to come from somewhere. Printing money to arbitrarily make it cost less is an option, but it’s one that functional governments don’t use because using inflation to make your debts not matter is a disastrous policy.