Is there a way to undo bank checking account reconciliation?

Yes, there's definitely a way to do that. The fastest method to start over is to invite your accountant and have them undo the entire reconciliation. They have a special tool that can reverse a reconciliation at once.

If you prefer to do it on your own, you can unreconcile the transactions one at a time on the register:

1. Go to the Gear icon, then select Chart of accounts.
2. Find your checking account and select View register.
3. Select each entry in the list to expand the view. Please know that reconciled transactions have an "R" under the checkmark column (✔).
4. Keep clicking the box with the "R" sign repeatedly until it's blank.
5. Click Save to confirm the changes.

When done, you can immediately start reconciling your checking account correctly.

Feel free to reply below if you have any other questions about managing your reconciliations.