My only issue has been when I open my App Store and it has the list of App Updates available when I try to update my apps it is trying to request his password and refuses to let me update my apps.
Each Apple device is linked/associated with an Apple ID of the person who did the setup.
To unlock the Phone, you need the Apple ID and password of the previous owner, in your case it is your father, that were used during set up.
Then your father has to read -> this Apple article: What to do before you sell, give away, or trade in your iPhone, iPad, or iPod touch
What to do before you sell, give away, or trade in your iPhone, iPad, or iPod touch - Apple Support
Then your father has to remove the iPhone from his account, see this Apple article:
Check your Apple ID device list to see where you're signed in
Check your Apple ID device list to see where you're signed in - Apple Support
Then you can sign in with your own Apple ID.
You can contact Apple support for help, -> Get Support (apple.com)
You have to show proof of ownership of your product, provide all documentation showing your purchase of the device.
If you do not have additional proof of ownership, contact the reseller. They may be able to provide the original purchase document.
Once Apple receive your proof of ownership, Apple will further review your request and provide an update.
