MYSQL

1>To See all users in the MySQl
SYN:-->
SELECT * FROM mysql.user; 

2>To drop user from mysql
SYN:-->
drop user username;

3>To know the column is in which table
SYN:-->
SELECT table_name FROM user_tab_cols WHERE column_name like '%COUNTRYCODE%';
We get the list of table names which contains the column name as COUNTRYCODE
O/P
TABLE_NAME
------------------------------
EMPLOYEE
USER 

IF error is ERROR 1396 (HY000): Operation CREATE USER failed for 

The Solution is 

drop user admin@localhost; 

flush privileges; 

create user admin@localhost identified by 'admins_password' 

To drop user from mysql SYN:--> drop user username;

To See all users in the MySQl SYN:--> SELECT * FROM mysql.user;