Someone a while back wrote a perl script called reduce.pl and posted it to psocdeveloper.com. I've attached it here. It will remove unused API functions, with one caveat, that is discussed in this link:
External code sublimator

This is the only way to remove unused APIs safely on a 29x part for the ICC compiler, and the only way I know of when using the HiTech compiler.

The forum forces certain file extensions for attachments, so I renamed the file to .lst. Perl usually used .pl, so just rename it to reduce.pl and you're good to go. Also make sure you have perl installed on your computer.

Aaron