Trying to be helpful: the FAQ entitled “How often is new data added to my Tiller-powered spreadsheet” contains the below text. However, the very last sentence is now out of date with the launch of Hello, Money (thank you Tiller team!)
What happens if I close one of my financial accounts?
When you close an account our data provider cannot pull in the final $0 balance for the closed account so you would need to manually add a balance history entry for the account to reflect the $0 balance.
You can also hide the account in your spreadsheet using the Hide option on the Accounts sheet.
There isn’t a way to change the balance to show as a $0 balance or exclude the account in the daily email at this time.