What are Faces?
Faces can be thought of as freely definable, infinitely thin, shaped areas that form part of an assembly. Faces can partially obscure or completely cover other faces (depending upon their z-values).
To delete any covering face:
1. Click Hidden and then, in the Modify group, click 
Delete Face.
Delete Face.2. Select the face.
 | The face to be deleted must be in the active part. |
In simple terms, you could imagine faces as pieces of paper, laid one on top of another, thus obscuring elements with a lower z-value.
The below figure shows the faces of two components (one with z-value 0 and the other with z-value 1).
Faces — With Z-Values 0 and 1
| | A face does not necessarily need to have the same z-value as its boundary lines. In this case, the boundary lines of the face may be partially covered by the face itself (solid lines may appear dashed in some cases). The linetype of the boundary lines is not changed. |
Faces are defined in one of the following ways:
• Automatic face search for an entire part (Creo Elements/Direct Drafting tries to find a maximum number of faces contained within a part. All faces are assigned the same z-value).
• Automatic face search for an entire part (with hole recognition).
• Automatic face search by clicking (similar to automatic hatching).
• Manual face specification (similar to manual hatching).