Hi there. I m working in autoCAD'13. I have got this drawing from a client. I need to trim these surfaces to get only the outer surfaces. But since these are not intersecting at right angles, i m not able to trim these surfaces. Any help will be highly appreciated.Please find attached a small part of the concerned drawing. The intersecting surfaces in the drawing have to be trimmed.

There appears to be no attachment.  Try again.

Guys this is the attachmentAttachment

Sorry, must have missed that subtle color change in your first post.

Hello rohit.jain092, I don't know precisely what you want to do with your surfaces and as when you select them, no grips are available but with an UCS seting ( option 3 points to have the good direction ) I was able to "trim" them with the command SUBTRACT by copying a surface and then subtract it to itself ( with a certain distance otherwise you erase it entirely ).
Hope this will help.
Ask for more.