I checked and it looks like you still have active proposals under your agency account. Please, make sure you withdraw them before closing the agency.
It looks like you have active candidacies on your agency profile. Please go to your proposals page, and withdraw the active proposals. Once done, please try to close your agency account again. Let me know if the issue persists.
Please withdraw all your active candidacies on your agency account by going to your proposals page, and withdrawing the proposals on the active tab. Let us know if you need further assistance.