In Magento 2 you cannot perform the reindex from the admin panel. To make a reindex you need use PuTTY or another terminal application to run the CLI commands, e.g. command for reindex:

php bin/magento indexer:reindex

With FREE Magento 2 Command Line (CLI) Extension by Magefan you can run CLI commands directly from Magento 2 admin panel.

To reindex from Magento 2 admin panel:

1. Install Magefan CLI extension to see a new menu item "System > Command Line" to be added to the admin menu.

Magento 2 Command webpconverted Line

2. Enter your current admin user password (for security reason) On "Comand Line" page and enter the reindex command.

Reindex Magento 2 From webpconverted Backoffice

3. Press ENTER to start the reindexing after you have entered the "php bin/magento indexer:reindex" command.

Result:

Reindex Magento 2 From Admin Panel

With Magefan CLI module, you can run any other Magento 2 commands.