rpm -qa | grep -i mysql

yum remove mysql-community-common-5.7.27-1.el7.x86_64
yum remove mysql57-community-release-el7-8.noarch
yum remove mysql-community-server-5.7.27-1.el7.x86_64
yum remove mysql-community-client-5.7.27-1.el7.x86_64
yum remove mysql-community-libs-5.7.27-1.el7.x86_64

rpm -qa | grep -i mysql

find / -name mysql

rm -rf /usr/lib64/mysql
rm -rf /usr/share/mysql
...

rm -rf /etc/my.cnf 

rm -rf /var/log/mysqld.log