I have added a file to google docs, which is not as similar to making a copy. It is like making a shortcut like thing (in windows terminology) or link like thing (in linux terminolgy) with a catch that if you remove any of the file the parent or the child both of them gets deleted.
My question is how to delete any one of them?
Searching something like this "removing added google docs" gives a completely irrelevant result.
Best Answer
Short answer
At this time it's not possible.
Explanation
I think that instead of seeing the Google Documents and the other Google editors apps like an OS file explorer we should see them as Google Search, so instead of asking how to "delete" we should ask something like
as the question of this title does at this time, or
So I imagine that the solution will be something similar to Google Custom Search or add-on that removes certain "search results", like Personal Block List (by Google)