Transfer of Projects from Old Owner

Good Afternoon, I need to change our origanization's Rise projects from the old owner who is not listed under our Account Manager. Since he is no longer listed under our account manager (he left the company over a year ago), the instructions at this link do not work for us: https://community.articulate.com/series/articulate-360-teams/articles/managing-content-when-users-leave-your-team#transfer-content