You can use the Photoshop painting and adjustment tools to edit the textures contained in a 3D file. Textures are imported as 2D files with the 3D model. They appear as entries under the 3D layer.
To display or hide an individual texture on a 3D model, click the Eye icon next to the Texture layer. To hide or display all textures, click the Eye icon next to the top level Texture layer.
For a video on editing textures, see www.adobe.com/go/vid0021.