My used iPad is locked to the previous owner

Without the Apple ID and Password of the original owner, you will never be able to use the device. Activation Lock is a theft prevention feature. Return for your money back or recycle the device at any Apple Store.

Troubleshooting a Locked iPad:

Have the Seller Log Out of This:

Learn from this:

If this is a used device, then the person currently signed in to the iPhone needs to log themselves out of it. Elsewise, it is useless to your account. This is the site the seller should have used, prior to selling it to you: What to do before you sell, give away, or trade in your iPhone, iPad, or iPod touch - Apple Support. The seller should have known better. So, return it, requesting that they log out of it, and that they use that post I just provided prior to handing it back in.