How do I set administrator menu to be the same as this Drupal 7 menu? I upgraded my site from Drupal 6 to Drupal 7.

The administrator menu is looks differently with Drupal 7 aministrator menu.

How do I set it same as the default Drupal 7 menu?

Drupal 7 administrator menu after upgrading



I want it became this administrator menu
To disable the menu shown in your first image, go to Structure > Blocks and disable any menu blocks you don't want to display (e.g., Management, Navigation, User). (Thanks, @leymannx!) 

To have the menu shown in your second image, enable the core Toolbar module.