local-infile=0 in your /etc/my.cnf

For security reasons, it's often a good idea to have:

[mysqld]
local-infile=0

present in your /etc/my.cnf file.

If you want to set all users except da_admin and root to not have that privilege at the mysql level, then login to mysql with the login/pass from /usr/local/directadmin/conf/mysql.conf, and run the query:

use mysql;
UPDATE mysql.user SET File_priv='N' WHERE user!='da_admin' AND user!='root';
FLUSH PRIVILEGES;
quit

NOTE that that above command will remove file access from *all* accounts on your system, except da_admin and root.. so just be aware that it's a global change.