You have to install another compiler. C::B only ships with MinGW (or nothing).
It's up to you to find a supported compiler.
See the list in the settings, find a place to download the compiler you want and set it up.
But without fixing your problem, you will still not be able to do anything.
If you can not delete (or overwrite) the file manually, another compiler can't do it also.
But to fix this problem, you are in the wrong place.
Search the web for this error or find a forum that supports windows 7 problems.