She's talking about reducing the number of transitions. As in, discouraging or limiting the medicinal and surgical interventions that people who are unhappy with their sex sometimes pursue.
She is not advocating for people to be exterminated or sterilised or anything like that. That is an absurd reinterpretation of what she actually said.
She does not specify any sort of medical procedure, and refers to people "dissociated from their sex", so she's probably talking about all trans people, including people who merely change their name, pronouns, and mode of dress.
That she specifically includes those who are happily transitioned shows that this is not motivated by compassion. By including them, she is making it absolutely clear that she wants to prevent people against their will from being able to transition. Most people who transition describe it as enormously benificial. She wants to reduce their number because she describes them as a "problem".
When criticizing what someone has said, please consider addressing their actual viewpoint, rather than some fantasy you've invented.
Here's a link. [ https://www.pinknews.co.uk/2022/06/03/helen-joyce-transgende... ] It contains direct quotes and video of her statements. Her statements quoted in the first section constitute support for involuntary eugenics; this means she is an eugenics advocate.