Activation Lock on a friends phone, help!

Recently, as of 2-3 days ago, my dad gave me his friends old iPhone 6S. I never knew my dad's friend still had his iCloud account still on it, and I updated the phone to iOS 15.7.4 (the latest for the 6S) and I'm current stuck on an activation lock. I would ask my dad's friend for the iCloud account to get past it but he forgot his account for years already and he doesn't use it anymore as he has a new one. Please I need help getting passed this lock, if anyone has any ideas as to how to be able to remove it or remove the iCloud account to use the phone fully it would be appreciated. Thank you for reading. (I'm new to the Apple discussions site, and this is my first post here so if I made a mistake on the topic or anything please let me know, thank you.)