Which on is correct? “Closed your account by/to 30/11/2020”
I've closed your account by 30/11/2020
I've closed your account to 30/11/2020
Neither of these makes sense. They are both incorrect.
You could say
I've closed your account until 30/11/2020. This means that you have closed it temporarily and you will reopen it on 30/11/2020.
or you could say
I've closed your account (effective) from 30/11/2020. This means that the account was/will be closed on 30/11/2020. There is no indication that it will ever be reopened.