1. Load Gerbers and Drill.
2. Using command "Build Composite" create a new layer which is the Gerber layer minus the drill layer. It will create a new layer which uses Top Layer (or whatever you select) minus Drill..
Here's more information about composite layers (which should help understanding how they are used):
https://support.numericalinnovations.com/support/discussions/topics/14000002419
Numerical Support Team