How to claim a bad loan to a business?

For the past 5 years, I have loaned money to a startup I founded, as a way of bootstrapping the company.  The company didn't work out, and ceased operations in 2020.  I believe I am able to deduct the amount of those loans (minus the remaining cash in the company's bank accounts, which was refunded to me as partial repayment of the loans), but I can't figure out how/where to do that.  Any advice?  Thanks!