How can I unlock my iPhone 6 without a computer and password

You forgot its passcode to unlock it?

If Find My iPhone is on you can try removing it from account signing into icloud.com/find This can take several hours and you’ll want to be on a WiFi network the iPhone users regularly. If that doesn’t work you’ll need a computer.

You can't. You need a computer to restore the device to remove the passcode. You will have to borrow a computer.