My Macbook Pro Retina 15" has a 250G H/D which is full. How do I identify what I can remove
I'd personally recommend using a tool like DaisyDisk to get a clear indication of what files are taking up the most space. 



After that you could also run a tool like CleanMyMac (paid) or MacClean (free) to help you delete more hidden files like browser caches and language files.