Remove editions of Windows 7 Iso

I downloaded an ISO of Windows 7 64 bits, I have a problem: I saw 4 editions in .clg files (home basic, premium, professional and ultimate), I opened install.wim with 7zip and I saw folders called 1,2,3 and 4. I suppose numbers are the 4 editions I mentioned. How to remove editions from ISO? My problem is those editions makes iso size be up to 5.5 GB. I just need ultimate, no more editions needed.