If I close a bank account, will I still be able to see past transactions in quickbooks?

Glad to see you in the Community, meg13.

If the account is connected to online banking, you can still see past transactions when you disconnect it. This will only stop QBO from downloading new entries. Make sure to add and match all pending transactions on the Banking page since it will delete any entries in the For Review tab.

Here’s how to unlink the connection:

1. Go to Banking on the left pane to select the Banking option.
2. Choose the account you're working on and click the Pencil icon.
3. Hit the Edit account info menu.
4. In the Account window, tick the box next to Disconnect this account on save.
5. Press Save and Close.

However, if you’re trying to delete the bank, you’ll no longer see it from the list of accounts. This is because the process is permanent. You’ll hold on to your old information on financial reports.

If the data on the removed bank shows in other accounts in QBO, it will stay from there. For more insights about these processes, check out the following guide: Disconnect or delete an account connected to online banking.

If this is for a manually added account, this link provides an overview of what will happen when you inactivate it and instructions to delete an account on your chart of accounts in QuickBooks Online.

For future reference here's an article that will guide you on how to: Manage default and special accounts in your chart of accounts. 

Reach out to me if you have any clarifications or questions. I’ll be glad to lend a helping hand. Have a great day ahead.