I'm sure a lot of people have come across this error message Error 1044 :Access Denied for user 'root'@'localhost' (USING PASSWORD:YES or NO) either because you have not uninstalled MySql properly/ simply because you are not using MySql logged in as a administrator/ using Mysql on your virtual machine having(Linux OS).
The solution is pretty simple, all you need to do is:
Type the following commands in your bash terminal in linux :
1. mysqladmin - u root password 'password goes here';
and then
2. mysql -h localhost -u root -p
and then enter the password when asked.
In case of Windows :
This solution also pretty much works for removing the above error provided you have given concerned users/all users 'FULL CONTROL' .