求指导如何decline Boulder....

之前口头decline掉了offer，前几天又突然冒出来MS的小奖....... 到网申系统转了N圈也没发现哪里可以decline，问了小秘他说：

Thank you for letting me know. In a few weeks you will receive an email from CU Boulder with your IdentiKey information – sign in to the portal as advised and decline the offer online. That will finalize your decline.

portal我进去了也没有发现可以accept/decline的地方。无力继续找了……要是一直不给确认信息会不会有关系，能被自动认为是decline吗？或者求大牛指点到哪里decline？...