All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none       worthy of worship except Allah, and that Muhammad 
  is His slave and Messenger.        
No real picture of the Prophet 
  has ever existed. The picture you mentioned is just an imaginary suggested depiction, not a real one. However, you can remove       that picture (cover it or erase it) and benefit from the rest of the book if it is useful.
Allah Knows best.