From another post I made some time earlier this year:
Courtesy of a post elsewhere on this site, I found this
TechNote, which explains how to hide such topics from the Search
feature in WebHelp:
http://www.macromedia.com/go/rb_19940
In a nutshell, you tag each topic you want to exclude from
the search, generate the output so that it excludes the tagged
topics, copy a few files in the whdata and whxdata folders to
another location, regenerate the output so that all topics are
included, and then overwrite those .HTM and .XML files with the
files you copied from the whdata and whxdata folders.
(Whew! Got all that?)
The upshot is that the final version of the WebHelp project
hides certain topics from the search feature but still includes
them in the compiled project.
IMPORTANT NOTE: If you are using WebHelp Pro, the steps are
quite different! You should publish the ENTIRE project first, and
THEN publish the files you want to exclude from the search
feature.