2001 October 24, Jim Quinn, “Re: Camp check”, in alt.games.everquest[1] (Usenet):
i ve added him to /friends and will tell him about this thread next time we are both on. then unadd him from /friends and forget about it.
2007, Philip Purser, Natural Terrariums, T. F. H. Publications, →ISBN, page 82:
Adding fertilizer to a terrarium is a lot like adding salt to a recipe: Once you've added too much, you can't unadd it, and you've likely ruined the recipe!
2011, Tim Phillips, Talk Normal: Stop the Business Speak, Jargon and Waffle, Kogan Page Limited, →ISBN, page 50:
Collaboration tends to be a one-way street: once you've added people to the project, it's hard to unadd them.