How to clear contents of table completely?

Pressing del simply doesn't do it. How can I clear contents of a cell or table completely ?

Edit: I thought it was pretty obvious by the question title and image, but what I want to do is empty the contents of the table, not delete the table. I want to also remove/clear the black coloring, but it simply won't go away. The coloring and the whole font and format of that colorful text below came from a copy and paste from my IDE in C++, CLion.

Edit2: I provided a working asnwer. Also note: I am on 2013 version.