how to change template?

you could use this snippet, and modify the output string accordingly.

$categories = get_the_category();
$separator=" ";
$output="";
if ( ! empty( $categories ) ) {
    foreach( $categories as $category ) {
        $output .= '<a href="' . esc_url( get_category_link( $category->term_id ) ) . '" alt="' . esc_attr( sprintf( __( 'View all posts in %s', 'textdomain' ), $category->name ) ) . '">' . esc_html( $category->name ) . '</a>' . $separator;
    }
    echo trim( $output, $separator );
}