Thanks for sharing.
Call customer care and tell them you don't want the card and not willing to activate it for whatever reason. They should be able to. If not, email. Even if email doesn't work then Principal nodal officer.
I don't need you need to pay if you haven't activated it. But in your case, since you are trying to close via app it could deem you activated the card. Take a risk and wait for a month. You will be asked to activate the card again. If you get such a message just ignore. Else you may have to pay up