Existing outlet is a 14-50R, new charger going in has a 6-50 plug.

How do I replace the 14-50R with a 6-50 receptacle and do the rewiring?

14-50R is a dual voltage outlet, 120/240. 6-50 is a straight 240. On the 14-50 you have 4 wires, 2 hots, 1 neutral and 1 ground. To install the 6-50. Use the 2 hots and a ground, cap off the neutral and push back in the box.

Thanks much.
Which hot goes to which blade?
And (dumb question) if I do this will the voltage be affected?

Thanks again

Does not matter, either hot can go to either brass terminal on device.

Thanks much.
Which hot goes to which blade?
And (dumb question) if I do this will the voltage be affected?

Thanks again

The original outlet supplied both 120 and 240. The new outlet will only supply 240 as noted for a 6-50 outlet.

Thanks to both of you. Just what I needed to know.