how to unlock disable iphone without using itunes

You can't. Here is the only way:

https://support.apple.com/en-us/HT204306

The only other alternative is to take the iPhone to an Apple Store and use their computers.

You will need a computer (Windows or Mac) to reset the passcode and erase all data so that the iPhone can be put back in service. There is no way around that. Try and borrow a computer from a family member or a friend.

Axel F.