I am unable to remove activation lock on my iPhone

You will need to show proof of ownership this can be done by printing out your installment agreement. You will need to upload this document with the serial # of the device written down in the upper right hand corner. If you outright own your device then you will need to supply Apple support with a copy of your original receipt. Buyers Name,Buyers Phone Number, Buyers Address,Device: (example) Apple 128GB and Installment ID. This document should also show Itemization Of Amount Of Amount Financed including Number Of Payments, Amount Of Payment, Monthly Payments Due. It helps if your installment agreement has the business name and address with the date of when you purchased the device. Example: your installment agreement Seller/Creditor: New Cingular Wireless PCS,LLC d/b/a AT&T Mobility (date) 08/15/2023 You then need to submit this document to Apple. Account verification has to be established with Apple support prior to submitting and the more proof you provide the better. After you submit your required information it will take 7-10 days to get a decision from Apple so be patient. This does not guarantee you anything from apple please stay mindful of that okay? Well I hope you got something out of this? Shalom

If they cannot remove the activation lock then it could be that you didn't provide authentic proof of purchase information to let the lock be removed I am afraid. Activation lock is a theft deterrent system so sometimes they won't remove it for you