If I paid an employee by direct deposit and missed paying him hours how do I correct this

Welcome to the Community. Let's go through the options available for you in this situation, @brookstristan29.

If the direct deposit paycheck is still unprocessed, you have the option to make changes to it in QuickBooks Online (QBO) Payroll. Press Edit on the paycheck in question, then enter the correct hours. Ensure that you Save the changes before 4:55 PDT 2 banking days before the pay date.

For processed direct deposit paychecks, you can still press Edit to enter your changes. Keep in mind that the net pay will remain locked to its original amount. A payroll correction is automatically added and will be resolved on the employee's next paycheck. 

View this article for additional information: Change an employee paycheck. It includes the steps on how you can edit manual paychecks as well. 

On the other hand, if you need to remove paychecks, keep this article for reference: Delete or void paychecks.

Feel free to post a reply in the comments below if you have other questions about editing paychecks in QBO. I'll get back to you as soon as I can. Enjoy the rest of the day!