We have a formal process for situations like this. You can read about the process here: https://leanpub.com/takedown.
We recommend you read the whole page, but we would particularly like to draw your attention the section on "Counter-Notification."
My book or course has been retired from sale on the Leanpub store due to a Notification of Infringement determination. What can I do?
Written by Leanpub Support