1.查看系统版本

cat /etc/centos-release

 2.停掉服务service postgres-9.6 stop

如果在运行，默认的5432端口就能被监听到

 3.卸载旧版本的postgres

yum remove postgresql*

[root@Adfuser-Test-2 etc]# yum remove postgresql*
Failed to set locale, defaulting to C
Loaded plugins: fastestmirror, refresh-packagekit, security
Setting up Remove Process
Resolving Dependencies
--> Running transaction check
---> Package postgresql.x86_64 0:8.4.20-8.el6_9 will be erased
---> Package postgresql-devel.x86_64 0:8.4.20-8.el6_9 will be erased
--> Processing Dependency: postgresql-devel for package: aam-adfuser-2.80.0-18_1.el6.x86_64
---> Package postgresql-libs.x86_64 0:8.4.20-8.el6_9 will be erased
--> Running transaction check
---> Package aam-adfuser.x86_64 0:2.80.0-18_1.el6 will be erased
--> Finished Dependency Resolution

Dependencies Resolved

================================================================================
 Package          Arch   Version         Repository                        Size
================================================================================
Removing:
 postgresql       x86_64 8.4.20-8.el6_9  @base                             14 M
 postgresql-devel x86_64 8.4.20-8.el6_9  @base                            3.4 M
 postgresql-libs  x86_64 8.4.20-8.el6_9  @base                            625 k
Removing for dependencies:
 aam-adfuser      x86_64 2.80.0-18_1.el6 @/aam-adfuser-2.80.0-18_1.el6.x86_64
                                                                           35 M

Transaction Summary
================================================================================
Remove        4 Package(s)

Installed size: 52 M
Is this ok [y/N]: y
Downloading Packages:
Running rpm_check_debug
Running Transaction Test
Transaction Test Succeeded
Running Transaction
  Erasing    : aam-adfuser-2.80.0-18_1.el6.x86_64                           1/4 
warning:    erase unlink of /etc/adfuser/tmp/aam_pkgs/aam_adfuser-2.80.0.post18-py2-none-any.whl failed: No such file or directory
warning:    erase unlink of /etc/adfuser/tmp/aam_pkgs/.must_exist_in_git_repo failed: No such file or directory
warning:    erase unlink of /etc/adfuser/tmp/aam_pkgs failed: No such file or directory
warning:    erase unlink of /etc/adfuser/tmp failed: No such file or directory
  Erasing    : postgresql-devel-8.4.20-8.el6_9.x86_64                       2/4 
  Erasing    : postgresql-8.4.20-8.el6_9.x86_64                             3/4 
  Erasing    : postgresql-libs-8.4.20-8.el6_9.x86_64                        4/4 
  Verifying  : postgresql-devel-8.4.20-8.el6_9.x86_64                       1/4 
  Verifying  : aam-adfuser-2.80.0-18_1.el6.x86_64                           2/4 
  Verifying  : postgresql-libs-8.4.20-8.el6_9.x86_64                        3/4 
  Verifying  : postgresql-8.4.20-8.el6_9.x86_64                             4/4 

Removed:
  postgresql.x86_64 0:8.4.20-8.el6_9                                            
  postgresql-devel.x86_64 0:8.4.20-8.el6_9                                      
  postgresql-libs.x86_64 0:8.4.20-8.el6_9                                       

Dependency Removed:
  aam-adfuser.x86_64 0:2.80.0-18_1.el6                                          

Complete!
[root@Adfuser-Test-2 etc]# 

4.验证是都卸载完毕

rpm -qa | grep postgresql