I use RedHat too.
Ok, since you cannot rpm --erase apache.rpm
you have to use a basic shell operation.
basically one way to get rid of most of it is with these
commands (as root because you need permission to delete the files)
user@host(/)# for file in `slocate apache`; do rm -rf $file ; done
user@host(/)# for file in `slocate httpd`; do rm -rf $file ; done
user@host(/)# rm -rf /var/log/httpd
that should clean it out decently.
at least 99.9% of the stuff will be gone that way.
hope that helps