系统环境：
Red Hat Enterprise Linux Server release 5.5 (Tikanga)
Oracle Database 11g Enterprise Edition Release 11.2.0.1.0
步骤如下：
1.停止所有Oracle进程
$ sqlplus / as sysdba
//for asm instance
$ sqlplus / as sysasm
SQL> shutdonw immediate
$ lsnrctl stop
2.删除Oracle安装目录
# rm -rf /u01/app
3.删除相关的用户和用户组
# userdel -r oracle
# groupdel oinstall
# groupdel dba
# groupdel oper
//for asm instance
# userdel -r grid
# groupdel asmadmin
# groupdel asmdba
# groupdel asmoper
4.删除相关配置文件
# rm -rf /etc/oratab
# rm -rf /etc/oraInst.loc
# rm -rf /usr/local/bin/dbhome
# rm -rf /usr/local/bin/oraenv
# rm -rf /usr/local/bin/coraenv
//for grid RAC
# rm -rf /etc/oracle
# rm -rf /etc/init.d/init.ohasd