Q: I noticed that touch id can be bypassed by swiping and entering passcode.  Is there any way to turn off the passcode, so the phone can ONLY be unlocked using your fingerprint?

What happens if the touch ID sensor gets broken?  It is a backup method to get in to your device.

Consider editing your lock screen passcode, changing it from a simple 4 digit code, to a longer more complex password.

HTH

What happens if the fingerprint reader breaks?

You lose your fingers that are registered in an industrial accident?

Your family needs access to your phone but you are dead?

Rather than re-invent the wheel you can find your answers here: iPhone 5s: Using Touch ID