You can convert simple holes to circular milled pockets, and you can revert the circular pockets back to holes. When you switch circular milled pockets to drilled holes, you must define a drill diameter in the machining template that matches the hole diameter, or that is at most 10 percent smaller than the circular pocket diameter.
You cannot convert holes that require tapping or counterbored holes.
For simple drilled holes, in the CostingManager, right-click the feature, and click Change to Mill. This converts the drilling operation to a milling operation. You can also drag the simple hole feature to the Mill Operations 
folder.
For circular milled pockets that are converted from drilled holes, in the CostingManager, right-click the feature, and click Change to Drill. This converts the milling operation to a drilling operation. You can also drag the circular milled pocket feature to the Hole Operations folder.