She has brought to a close her three-year stay at the Club after declining a new contract and accepting an offer elsewhere.
The 30-year-old midfielder joined Blues from Bayer Leverkusen in April 2016.
Ewers, who previously played for Club Hamburger SV, has served three managers in David Parker, Marc Skinner and Marta Tejedor, making 28 appearances.
While at the Club, Ewers had been juggling studying for a Masters degree in Sport Management, graduating from Birkbeck, University of London. She travelled into the city during the week, whilst continuing to train with Blues.
The Club would like to thank Marisa for all her efforts and wish her every success in the future.