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See if this support article can help you:--> If you forgot your Apple ID - Apple Support
If you are talking about "activation lock" (an anti-theft measure), neither we, just users like you, nor Apple can help you, sorry, unless you are the original owner and you still have the proof of purchase (receipt/invoice reporting your device’s IMEI or Serial Number). Should be this case, start your request using this link: https://al-support.apple.com/#/additional-support
Shouldn’t be this case, activation lock can be removed only by the previous owner, with the credentials that were used to activate that iPhone/iPad. Without those credentials, that device is useless to you.
You can also take a look at this support article:--> How to remove Activation Lock - Apple Support
Regards
Giulio