Can't delete code injected

Site URL: https://iris-lizard-4zg7.squarespace.com

Hi guys, 

I've copied this code into the code injection section but now I can't get rid of it by selecting the text + delete. Any shortcut? Why is this happening? 

Thanks, 

D.

If you use Personal Plan, you can't remove code in Code Injection.

The code there is also ignored when you use the Personal Plan. It only runs when you are in Trial Plan or Business Plan or higher