Do you have the iPad Passcode - and the current AppleID Password? Are you able to access iPad Settings?
If the answer to all of these questions is “yes”, then it is a relatively simple task to sign-out and sign-in with a different AppleID - creating a new AppleID account is required. Before doing so you must review where your data is stored - and/or create an appropriate backup of the data before proceeding.
If the answer to the above questions is “no” - if you don’t have an existing iCloud or iTunes backup of the iPad, then access to any locally stored data has already been lost. The iPad has an encrypted filesystem; if you don’t have the required credentials to access the device, the encrypted data is beyond reach.
If you can provide more information about the precise status of the device (such as having access to its settings, it being Disabled or Activation Locked) - and whether or not you have the Passcode and AppleID credentials, more specific advice and guidance may be possible.