A RPM installation of LispWorks can be uninstalled in the usual way, for example by executing this command, as root:
rpm --erase lispworks-7.0
If patches have been added via RPM, then you will first need to uninstall that package, which will be named lispworks-patches7.0. The same applies to additional RPM packages such as lispworks-sql.
If patches have been added from a tar archive, you will need to remove them by hand.
If you installed LispWorks from the tar archives, simply do
rm -rf /usr/local/lib/LispWorks
LispWorks Release Notes and Installation Guide - 2 Mar 2015