Because of load of work, we hire a freelancer to manage one of our forum and going to give him user/pass of Cpanel.

But we want to secure or database, Is there any option in Cpanel which disable phpmyadmin or export command in it.

No problem if this option Off for all accounts. We have root access.

If you are using WHM you can create a custom features list for that account and remove phpmyadmin from the list as well as any other features you don't want said freelancer to access.

as per my last experience about features list. It can't disable feature its only disable shortcut (icon) if use manually type url, he can reach that feature.

Important security consideration. Even if you disable him access to the phpMyAdmin, but at the same time leave the access to the file system, he would be able to retrieve the database contents from within PHP.