Do I need to deauthorize an iPad before I erase it?

No. iOS devices are not autohirzed or de-authorized like computers are.

Erasing it correctly severs all connection yo your account and clear all data from the device.

If you are trying to completely clear the iPad, see the steps in the following: What to do before you sell, give away, or trade in your iPhone, iPad, or iPod touch - Apple Support