Here is a document:
http://service1.symantec.com/SUPPORT/ent-security.nsf/docid/2006022212084148?Open&docid=2002031914291648&nsf=ent-security.nsf&view=docid
It is recommended that the following procedure be used:
a) Disable services
b) Remove everything possible using rmdir /s while terminating processes
c) Reboot
d) Disable one more service
e) Complete the task using the Revo Uninstaller tool (see previous post).