You can use almost any brand wire. I like to use TQ Wire because it is more flexible and doesn't have overly thick insulation.
To remove the old XR10 wires off the ESC, cut the wire near the soldering posts. It should be a lot easier to remove. The problem when you try to unsolder the stock XR10 wires is the rest of the wire absorbs the heat when you try to unsolder it.So the solder doesn't get hot enough. When you cut the wire near the post, it is a lot quicker to remove the remaining end with an iron, since it heats up very quickly.
I will pick up some TQ wire at my lhs and rewire my XR10. Thank you for the advice on cutting the wires shorter for ease of de-soldering them.