Installing one wire alternator

All you need do is safe the old wires off.

If you are (you didn't say?) working on a 69/ earlier, there is only a "hot" switched wire to the VR (IGN), dark blue, and then the green becomes disconnected at both ends

On a 70/ later system, the connector for the VR pretty much IS safe unless you want to cut it off and hide it, so tape off the blue. The green will no longer go anywhere

At the alternator, the blue field wire is switched 12V so it also needs to be taped/ safed off