How to completely remove EnterpriseDB Installation of Postgresql on Ubuntu?
In Feb 2009, Scahin_S  wrote in [1] to use the uninstall-postgresql binary.  In the same thread Sachin_S also documented a manual alternative for uninstalling 8.3 is

/opt/PostgreSQL/8.3/installer/server/removeshortcuts.sh /opt/PostgreSQL/8.3 8.3 
/etc/init.d postgresql-8.3 stop 
rm -rf /opt/PostgreSQL 
rm /etc/postgres-reg.ini 
rm -rf /etc/init.d/postgresql-8.3 
userdel postgres 

if /etc/ld.so.conf exists, edit it and remove /opt/PostgreSQL/8.3/lib 
if present. 

if /etc/ld.so.conf.d exists: 

rm /etc/ld.so.conf.d/postgresql-8.3.conf


1 - "Uninstall Postgres" thread
Enterprise DB "PostgreSQL Installers for Windows, Linux and OS X" forum
http://forums.enterprisedb.com/posts/list/1437.page