With Adobe Photoshop CC (2014) there are several ways to remove a face from a photo. A Mosaic filter works well for pixelating a face, making the person anonymous, but still obviously human. Blur filters can also work, making the portrait look rather ominous like something out of a horror movie or Slender Man game. For a blank mask effect, try using just the Paint Tool. Adding black dots for the eyes and a line for the mouth to a blank mask can make the face either comic, or extraterrestrial, depending on the colors used and the size of the eyes.
Create a duplicate of the photo's layer by dragging the "Background" layer onto the "New Layer" button in the Layers panel.
Select the "Magnetic Lasso Tool," "Lasso Tool" or "Polygonal Lasso Tool" from the Toolbox. Drag the cursor around the outline of the face to select it. Press "Ctrl-C" to copy the face and "Ctrl-V" to paste it into a new layer.
Click the "Filter" menu, select "Pixelate" and click "Mosaic." This filter uses large square pixels, retaining color tones but obscuring recognizable details.
Drag the "Cell Size" slider to specify how large the pixels should be. The setting depends on the size of the face and the resolution of the photo.
Zoom in and out of the photo to ensure that the face is pixelated enough to make the person anonymous, but not so blurry that you can't tell it's a human behind the pixels.
Click the "Magnetic Lasso Tool" in the Toolbox, or one of the other Lasso tools if you prefer. Select the face by dragging the cursor around its outline.
Click the "Select" menu, then click "Color Range." Click on a cheek or the forehead and then drag the "Fuzziness" slider so that most of the face, excluding the eyes, nostrils and mouth, are highlighted in the Preview thumbnail. Click "OK" to select those pixels. Click "Inverse" under the Select menu so that the eyes, mouth, and other areas of the face that are lighter or darker than the cheeks are now selected.
Select the "Eyedropper Tool" from the toolbox and click on the cheek to select that color. Click the "Brush Tool" in the Toolbox and then paint over the entire face. This paints over most of the facial features, making the face relatively blank.
Select "Blur" from the Filter menu and select "Motion Blur." Change the Angle to "90" degrees and drag the "Distance" slider until the important details are blurred from the face. Click "OK," and then look over the photo to ensure it looks the way you want it to.
Select the face with one of the Lasso tools. Click on the forehead or cheek with the "Eyedropper Tool" and then paint in the selected area with the "Brush Tool." This creates a blank, featureless mask over the face. You can also try different colors, like white or black.
Click the "Foreground Color" in the Toolbox after applying a blank mask. Change the color to black and then use the "Brush Tool" to draw two eyes and a mouth. Depending on what you're using the photo for, this may look better than just a blank mask.
Use Color Select to remove most of the details from the face as you would before applying the Motion Filter. Before applying that filter, however, add a thin horizontal black line over each eye and the mouth. When you apply the Motion Blur filter, change the angle to "180" instead of "90." The lines help create a more sinister faceless effect with the Motion Blur.