How do you complete level 11?

I am stuck at the end of level 11:

1) How to delete the "you deleted reality" in 6 key stokes?
2) Where do I find the Red key for the underground?

You don't need to "delete reality". These are simply provided for yanking. In regards of the red key here is a quote from the author:

Make sure you change the Open Sesame on Arrow Island according to the hints (and not just type them in). It's like in level 5 when you can edit the text, but the ranges are not shown.

1. As @firedev said, you don't need to delete reality. Those are there to let you get text into the "register" (similar to "clipboard") for pasting, before you have the y key for "yanking" (similar to "copying").
2. At the end of level 11, you get the red key by changing Open Sesame to :e underground. A red key and an NPC with a helpful hint then appear.