Here is Apple’s information about the Activation Lock - and how to switch-off this feature:
https://support.apple.com/en-us/HT201365
https://support.apple.com/en-gb/HT201441
As you will discover, if the iPad has been activated and associated with an AppleID account that you do not control, you will need to secure the cooperation of the account owner to whom the device is locked. If you cannot secure their cooperation, you’ll not be able to technically defeat or bypass this security measure. In this situation, there is nothing that anyone here can do to help.
If you are the original owner - and have documentary evidence (i.e, the original sales invoice that shows the device serial number), then Apple may be able to assist.
Sorry, this is perhaps not the news that you we hoping to hear.
However, if the iPad is Activation Locked by your own AppleID - and you have forgotten your AppleID or password, these can be recovered here:
To recover your credentials, you’ll need access to 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
Unless you AppleID account has not been fully/correctly configured, or has been seriously neglected, recovery of the AppleID and password should not be difficult.
More information about recovery of your AppleID:
https://support.apple.com/en-us/HT201354
More information about recovery of your AppleID password: