L had a electrician run wire from the panel to my new heater however the job was not complete
The heater has only two wires one red and one black
Yet he ran three 10.2 wires red,black and white so were do l go from there

You can use the black and red and cap the white, is the simple answer. However, one end needs to be properly connected to the panel and a circuit breaker, and the other to the heater, using proper cable connectors, wire connectors, etc.

I have to assume you do not have any experience in working with wiring?

What he ran was 10/3, not 10/2. All you needed was 10/2 though.

Why not have him hook up the water heater?

I would use the black and red as the hot legs, and the white as a case ground. Just be sure to mark the white at both ends with green marker tape to designate it as a ground and not a neutral, and be sure it is on the ground bar instead of the nuetral bar in the panel if you have an unbonded system.

White cannot be re-tasked as a ground conductor.