I hope you're enjoying the day so far. It's great having you here in the QuickBooks Community.
In QuickBooks Online, it will depend on the processing time of your payroll service if you can delete or void the paycheck. I've included some steps below that cover how you can delete the paycheck.
Here's how:
From the Home tab, under Related Activities, select View Paycheck List.
Click on the paycheck you'd like to delete, then hit Delete.
However, if you cannot delete the paycheck, you'll need to contact our Payroll Support Team. This way, an agent can void the paycheck for you.