he can't, imagemagick is not installed and osclass don't let you change that option, that is why i said what i said
But you said that happened because he transfered his site from an other hoster. And that didn't happen.
All-in-all, i doubt this is the case and if it is, then why it happened ?
Also in his Cpanel (not Osclass) Imagich extension seems installed and activated. As far as i know, that is enough.
Anyway, best for him is to start from scratch.