Unmerge an incorrect family tree

My name is Phyllis Marsha Anker (Katz) My family tree consists of my grandparents Philip and Rosa (nee Massey), my father Leo, his siblings Jesse, Alexander, Paul, and Hilda.  They were not from Vienna. Somehow other names have appeared and I received this email:

"I don't think this is a correct merge into my branch. My Philipp and Rosa Katz (nee Fichmann, not Massey), with children Leo, Gertrude, Alize and Jella, all lived in Vienna and none ever emigrated to the United States.

Kind regards,