You can remove a user access to database via the control panel (cPanel) tool. The administrator needs to navigate to the cPanel ' MySQL Databases' panel, and this panel provides the functionality to remove access to the database for a particular user.
Hosting Account->Manage->cPanel(quick links)->Databases-> MySQL Databases
->Current Databases-> Users
On the current databases section of the page the administrator can select user via the ‘cross’ button and this action will remove database access to that user.