This worked for me. Hopefully this works for you too!!! Follow them.
brew services stop mysql
pkill mysqld
# NB: the following command will REMOVE all your databases!
# Make sure you have backups or SQL dumps if you have important data in them already.
rm -rf /usr/local/var/mysql/
brew services restart mysql
mysql -uroot
UPDATE mysql.user SET authentication_string=null WHERE User='root';
FLUSH PRIVILEGES;
exit;
mysql -u root
ALTER USER 'root'@'localhost' IDENTIFIED WITH caching_sha2_password
BY'YOUR_PASS_WORD!!!!';