All Client option is available in admin panel >> Client >> All Client. 
If you will add your own Client (s) in your theme , then Client (s) list will be show here .
From on hover on any Client you will get below given option(s)
1. Edit :If you will hover on any Client in list, you will get edit option edit, by clicking on that you will be on edit Client , from there you can edit Client info like featured image, portfolio project link, Client title / name, page link etc...
2. Quick Edit : By Quick edit you can edit some most information(s) like Client Title , Slug , Status etc...
3. View : View Option is for view your Client on your website. If you want to see your Client with your matter like Title , Description etc... you can use this option.
4. Trash : Trash option is use for delete Client (s).
Bulk Actions : [3,5] You have all Client (s) list in below given image , if you want to take bulk action on one or more then one Client (s) , you can mark and select Your bulk action like delete etc...
** If you want to add a new Client you can click on Add new Client option.