I want to remove theme name and wordpress version from dashboard

Modify your Style.css in themes folder !

can u tell me how..

Try it with this in your theme’s functions.php [untested]:

function my_admin_head() {
  $screen = get_current_screen();
  if(is_admin() && ($screen->id == 'dashboard')){
    echo '<style>.versions p, span#wp-version-message { display: none; } </style>';
  }
}

add_action('admin_head', 'my_admin_head');

wp-content/themes/yourtheme/style.css