Disable Term (Category) Page Header Images When Adding a Thumbnail

// Option 1: disables the page header image completely.
add_filter( 'wpex_enable_term_page_header_image', '__return_false' );

// Option 2: Sets the default to disabled so you can still enable it if wanted via the category settings
add_filter( 'wpex_term_page_header_image_enabled', '__return_false' )