Which on is correct? “Closed your account by/to 30/11/2020”

Given some modifications the two sentences can be made sense of.

• I've closed your account, and I'll reopen it by 30/11/2020. (This means "I'll reopen it not later than 30/11/2020)

• I've closed your account for a period to end 30/11/2020. (The period will end precisely on 30/11/2020, at a given time on that day, depending on how days are counted.)
  If an event "ends on" a day, does the day constitute a part of the event?

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.