How can I remove “Category:” on title

Hi, Thank you for this amazing theme. It's really useful for me. I want to remove "Category:" word on title. (Not with CSS, I want to show the title) I checked .php codes but I didn't understand how. I found where all the "custom header titles" comes from. But can't figure out how to remove that. Exaxmple: I create a category called "DISCOGRAPHY". I want to sho title as only "DISCOGRAPHY" not with "CATEGORY:". here is the link: http://gulecmusic.com/site/category/discography/