I'm using one plus two. I tried everything but still the option 'USB tethering - USB not connected' is like this and I'm not able to able or disable it, it's Grey.... Please help me guys
Here is a checklist of what you need:
Is the cable you are using the official one that came with the phone? Some third party cables are untrustworty
Is your computer's USB socket working correctly and transferring data? You can check this by plugging in a simple USB flash drive. This is the most likely problem because android should enable this option as soon as it detects it is connected to a computer.