Syntax:
REVOKE
    priv_type [(column_list)]
      [, priv_type [(column_list)]] ...
    ON [object_type] priv_level
    FROM user [, user] ...

REVOKE ALL [PRIVILEGES], GRANT OPTION
    FROM user [, user] ...

REVOKE PROXY ON user
    FROM user [, user] ...

The REVOKE statement enables system administrators to revoke privileges
from MySQL accounts.

For details on the levels at which privileges exist, the permissible
priv_type, priv_level, and object_type values, and the syntax for
specifying users and passwords, see [HELP GRANT].

When the read_only system variable is enabled, REVOKE requires the
SUPER privilege in addition to any other required privileges described
in the following discussion.

Each account name uses the format described in
https://dev.mysql.com/doc/refman/5.7/en/account-names.html. For
example:

REVOKE INSERT ON *.* FROM 'jeffrey'@'localhost';

The host name part of the account name, if omitted, defaults to '%'.

To use the first REVOKE syntax, you must have the GRANT OPTION
privilege, and you must have the privileges that you are revoking.

To revoke all privileges, use the second syntax, which drops all
global, database, table, column, and routine privileges for the named
user or users:

REVOKE ALL PRIVILEGES, GRANT OPTION FROM user [, user] ...

To use this REVOKE syntax, you must have the global CREATE USER
privilege, or the UPDATE privilege for the mysql system database.

User accounts from which privileges are to be revoked must exist, but
the privileges to be revoked need not be currently granted to them.

URL: https://dev.mysql.com/doc/refman/5.7/en/revoke.html

