At this time, there isn't a way to delete states from the Payroll Taxes. I'm going to submit feedback to our Product Development Team about bringing in a feature that will allow this to happen. You can visit our Blog to see what's new in QuickBooks Online and what features are coming in the future. In the meantime, I'd like to explain more about what states show for Payroll Taxes.
When you set up Payroll, you’ll have to enter the necessary details including the work location and employees’ addresses. QuickBooks generates the forms and taxes to set up based on the employees’ residence and work locations. The states will appear in the Payroll Tax Setup. We want you to stay compliant with your tax regulations, which is why the software will require and prompt you to enter the information for each state. Even if the business and employees are in different states, some agencies have reciprocity agreements and may require employers to file and pay taxes for each one.
If you don't need the states, I recommend entering 0 for the rates and input dummy account numbers for the time being. You can consult with your accountant for advice on this situation.
Let me know if you have additional questions or concerns with QuickBooks. I'm always here to help. Best wishes to you and your company!