how do i completely reset an ipad to factory settings that i have no codes for

This is a mistake many companies make when they don't use Managed Device Software on company owned assets.

You'll need to find the original purchase receipt with the iPad Serial Numbers on it to get Apple to help you. Without that, you likely have devices which will be useless to anyone. Hopefully, the receipt was retained somewhere.

You're welcome and good luck. If your company routinely dispenses devices to employees, see this link about Apple Managed Device Software to avoid this in the future --> Intro to mobile device management - Apple Support