Possibility to leave the USB 5v and Gnd unconnected and still pairing to a comp?

Dirkhens:
For a project I am working on space matters a lot. So I took the USB connector off my UNO and use 2.54 pins to connect a usb cable on the underside of the UNO, which works a charm.

So dump the UNO and use a Pro Mini, huge space savings.

Whilst you may understand what you mean by '2.54 pins' a lot of people might be puzzled as to why you are cutting pins up so that you have 2.54 of them.