Any attempt to reset the iPad will trigger an Activation Lock - that will need to be satisfied before being able to reuse the iPad.
The key to your dilemma will be recovery of the AppleID credentials that currently secure the device(s)...
If the associated AppleID or associated password has been forgotten, or are unknown, they may be recovered here:
https://iforgot.apple.com/
To recover the credentials, you’ll need access to any one of the following:
- The primary email address mailbox that corresponds with the AppleID
- Any of the secondary/recovery email addresses that should be configured for the AppleID account
- Any of the trusted telephone numbers (fixed line or Cellular/Mobile) that are associated with the AppleID
More information about recovery of your AppleID and associated Password:
If you forgot your Apple ID - Apple Support
If you forgot your Apple ID password - Apple Support
Having recovered access to the AppleID account (and therefore the AppleID username and associated Password), Activation Locks can be removed. There are several routes to this, but for brevity, I’ll refer you to this support page:
Turn off Activation Lock – Apple Support
If your intent is to wipe/reset the device(s) for reuse by a new user, you would be best advised to prepare them properly:
What to do before you sell, give away or trade in your iPhone, iPad or iPod touch – Apple Support
If you are unable to recover or reset the AppleID credentials - and/or you encounter an Activation Lock - here are the Apple support pages that outline the Activation Lock - and the only mechanisms by which it can be satisfied:
Activation Lock for iPhone, iPad, and iPod touch - Apple Support
Turn off Activation Lock – Apple Support
As you will discover, unless you are the owner of the AppleID that was last used to activate the device, you’ll not be able to defeat or bypass the Activation Lock. With documentary evidence that you are the original owner (such as sales receipt showing the serial number), Apple may be prepared to assist - otherwise they and nobody here will be able to help you.
If you have the necessary documentation, Apple have introduced a portal though which you may be able to request release of an Activation Lock:
How to remove Activation Lock - Apple Support & start an Activation Lock support request.
However, this isn’t necessarily the end of the story...
A close Family member or Executor, with the required supporting paperwork, can make application to Apple to be granted access to the Apple accounts of the deceased:
How to request access to a deceased family member's Apple accounts - Apple Support
