yum remove mysql mysql-server mysql-libs mysql-server然后查看mysql安装了哪些东西
rpm -qa |grep -i mysql开始卸载
yum remove mysql-community-common-5.7.20-1.el7.x86_64
yum remove mysql-community-client-5.7.20-1.el7.x86_64
yum remove mysql57-community-release-el7-11.noarch
yum remove mysql-community-libs-5.7.20-1.el7.x86_64
yum removemysql-community-server-5.7.20-1.el7.x86_64查看是否卸载完成
rpm -qa |grep -i mysql查找mysql相关目录
find / -name mysql删除相关目录
rm -rf删除/etc/my.cnf
rm -rf /etc/my.cnf删除/var/log/mysqld.log（如果不删除这个文件，会导致新安装的mysql无法生存新密码，导致无法登陆）
rm -rf /var/log/mysqld.log