You don’t have to reverse the wires, GRBL can handle that.
In Easel, you’ll go to Machine → Advanced and in the Console, you’ll need to modify five GRBL configurations:
$3 will flip the Z axis direction to go from stock to direct drive. You’ll need to look at your current value and change it according to the GRBL Wiki page:
If you’re already inverted, you’ll need to not invert.