This function removes the default WordPress ‘Posts’ (blog) post type.

// Removes Default WordPress Blog Post Type

function remove_default_post_type() {
    remove_menu_page( 'edit.php' );
}

add_action( 'admin_menu', 'remove_default_post_type' );

// Removes Quick Draft Dashboard widget

function remove_draft_widget(){
    remove_meta_box( 'dashboard_quick_press', 'dashboard', 'side' );
}

add_action( 'wp_dashboard_setup', 'remove_draft_widget', 999 );