Use Intersect Faces to trim or break intersecting faces. Perform in conjunction with Extend Faces to ensure that faces intersect.

Open a file that contains surfaces and enter the repair or construction environment.
On the ribbon, do one of the following:
Modify panel
Intersect Faces.
Surface panel
Intersect Faces.Choose one of the following methods to select surfaces:
Trim. Click Trim, and then select two intersecting surfaces, making sure to select the area you want to keep. Surfaces are trimmed to the intersection.
Break. Click Break, and then select two intersecting surfaces. The surfaces are split at the intersection. All are placed in the same browser group.Continue to click Trim or Break and select surfaces in the graphics window.
When finished, click Done.