Is there any way I can change the end date of a reconciliation once it's completed? I have balance issues due to removing 3 reconciled transactions.

Yes, there are two ways you can change the end date of a completed reconciliation, @kim-reddick. Also, I'm here to ensure you're able to resolve its balance issues in the program. 

If your accountant isn't connected to your QuickBooks Online (QBO) account, let's go to the Account History page. From there, you can manually unreconcile each transaction from a completed reconciliation. That way, you can reconcile it with the correct ending date. As a reference, I'd suggest printing a reconciliation report to determine those transactions. Once done, proceed with the steps below. 

1. Go to Accounting from the left menu.
2. Select Chart of Accounts.
3. Locate the appropriate account.
4. Choose Account history from the Action column. 
5. Select the transaction
6. Go to the Check (/) column and click the box many times until it is blank. 
7. Hit Save. 
8. Repeat the process for other transactions within the reconciliation period. 

The screenshot below shows you the sixth to seventh steps. For detailed instructions, see Step 2 through this article: Undo And Remove Transactions From Reconciliations. 

Then, let's use the Audit Log to re-enter the three deleted transactions. After that, reconcile the account again with the correct end date. It's already balanced if the difference is zero. 

If your accountant is connected to your QBO company, I'd recommend getting in touch with them. They have a specialized tool to undo the entire reconciliation so you can change its ending date. Also, they can help you review all your transactions to ensure your books are accurate. 

As always, you can visit this resource hub: Reconcile Workflow. It contains in-depth details about starting, fixing any differences, and completing the reconciliation process. Just click the links beside QuickBooks Online. 

Please let me know if you need anything else. I'll gladly help, @kim-reddick.