I am having trouble undoing a previous reconciliation. There is no drop down for undo???

Good to see you here, mfilincieri.

QuickBooks Online offers two options to undo a previous reconciliation. You can either invite an accountant and have him/her use the accountant tool to undo a reconciliation. Another option is to open the register and double-click on the R to remove it one at a time. I'll show you how:

1. Select Accounting from the sidebar menu.
2. Go to Chart of Accounts.
3. Find the account holding the transaction, then click View register from the Action column.
4. Select the transaction you want to unreconcile to expand the view.
5. Review the check column. You’ll see an R if the transaction is reconciled.
6. Keep clicking the checkbox until it becomes blank to the transaction from the reconciliation.
7. Click Save, then close the account register.

Also, here are some articles that you can read to help resolve common reconciliation mistakes and errors:

• Fix issues for accounts you've reconciled in the past in QuickBooks Online.
• Fix issues at the end of a reconciliation in QuickBooks Online.

I'm just a post away if you need more help in reconciling your accounts. Stay safe!