I want to reinstall my Wordpress but it said I must delete old tables first .However, I can't know what're the tables was created by WP and I can't delete any table because of the error : Error: Access denied for user 'doanduy_clanteam_com_doanduy'@'10.10.124.196' to database 'information_schema'

What that is saying there:

Is that the user or "doanduy_clanteam_com_doanduy" isn't a user with access to delete the file/folder.
Do you have an phpMyAdmin Root user account?
They will also have a table prefix so you know what was created by WordPress Installer.

Why don't you just backup the SQL and then delete the whole WordPress folder and reinstall a new one?

Jacob.