I believe this claim is misleading.
Diving into this case it seems that there was a trans-woman in the women's locker room shaving their face. She was not harassing or hurting anyone. The woman, Patricia, posted a picture of the trans-woman online and put in a complaint to the company.
Planet Fitness stands by trans-women in a women's locker room.
The woman who shared the photo online was banned from planet fitness. She has a biased opinion on this issue and this claim is exaggerated. Those who are uncomfortable with the situation are threatening to boycott Planet Fitness. No where does it say that the boycotting is successful or even in-progress.
https://www.dailymail.co.uk/news/article-13206823/Planet-Fitness-trans-locker-room-video-alaska-response.html