How can I factory reset my iPad?

this is how you factory reset it How to factory reset your iPhone, iPad, or iPod touch - Apple Support

though that will not help to bypass an activation lock

activation lock is not a thing on the ipad it's a theft protection on apples servers

it needs to be removed How to remove Activation Lock - Apple Support

if you don't know your appleID password If you have forgotten your Apple ID password – Apple Support (UK)

then you will need the assistance of apple Activation Lock - Support (apple.com)

and or

Apple Support

And or

Contact - Official Apple Support

and or

Genius Bar Reservation and Apple Support Options - Apple

You will need to follow this process to prepare the iPad for use by its new owner:

What to do before you sell, give away, or trade in your iPhone or iPad - Apple Support

You will need your own AppleID credentials - as without these you will not be able to release the Activation Lock that will otherwise prevent reuse of the iPad.

If you have forgotten your AppleID or associated password, these can be recovered here:

https://iforgot.apple.com/

To recover your credentials, you’ll need access to any one of the following:

• Your primary email address mailbox that corresponds with your AppleID
• Any of the secondary/recovery email addresses that should be configured for your AppleID account
• Any of the trusted telephone numbers (fixed line or Cellular/Mobile) that are associated with your 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