Hi @TK ,
Welcome to our forum.
As I know, there may be no option that could check declined meeting and auto-cancel it in Outlook.
For your requirement, I have researched a lot and found some related vba scripts that mentioned how to check declined meeting response and perform any operations on it. So as a suggestion, please try to refer to these articles and develop your macro to check:
Accept or decline a meeting request then forward or copy it
Outlook meeting cancelling using VBA
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Hope that would be helpful to you.
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