Another way to create a hole in any surface is to choose a vertex point at the center junction of any 4 adjacent polygons, and cut edges from the corner vertices of the polygons, to the center vertex.  So the edges will look like a star.  This creates the necessary 8 edges to create a circle.  Now, select the center vertex, and chamfer it....

Then just use Geopoly tool to make the ngon a circle shape, and delete it, or extrude it, or whatever.

Or, just delete the faces, select the border edges, switch to edge mode, go to loop tools, and click Circle in the Loop Tools.  Either way works.  This is a good way to create any circular shaped extrusion or bevel, or simple circular holes, because unlike creating round shapes with Turbosmooth or Meshsmooth on a square, you won't need more than 1 iteration of smoothing to get a perfectly round shape in your surface.  Saves on polycount dramatically, and avoids booleans.

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