I imported an obj. file to Adobe Photoshop CC 2015 and the whole 3d model came as a single layer. It is a 3d racing suit model and I want to delete arms of the suit. I know I could use the quick selection tool and make a new layer from arm parts but since it is a 3d model, this method doesn't work on 3d meshes. I also tried the cross-section method but it too didn't work. I searched everywhere but couldn't find a proper method. Is there a way to select a part of a single 3d mesh, make a new layer out of it and delete it or simply erase a part of a single 3d layer?
According to Adobe, it's not possible.
To edit the polygon mesh of the 3D model itself, you must use a 3D authoring program.
So your best option would be to use a 3D software to do the job. Cinema4D, Blender, Sketchup, 3dMax and Maya have free versions and should be enough for what you need.
Use a free 3D Program like Blender or similar to edit the .obj and just delete the Polygons of the Arm.