My uncle gave me iphone but he forgets his icloud id now this phone is on iphone locked to owner pls anyone guide me how to solve it

Tell him to check his web browser autofill entries and other records, or use Apple's iForgot service, or contact their Account Security team, or the iPhone's original owner to click here and submit an unlock request.

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Without that information, the iPhone will be forever useless. We cannot get this information for you, and neither can Apple. Have your uncle start here:

If you forgot your Apple ID - Apple Support