Unfortunately, there is nothing you can do about it.

Once you start having intrusive thoughts about the therapist, it means your therapy has entered the sad (IMO) transference stage.

One thing that has a slim chance of making this situation better is if you talk to your therapist about it and if they take it seriously and explore these thoughts with you extensively and also if they show appreciation of your courage to talk about it. So, under those conditions, MAY BE (and it's a big "may be") the thoughts won't be as intrusive as they are now. But the chances are they still will be intrusive.

I don't claim that I "know" exactly how this works. All I know is what I know from my own experience and from what other people have been saying about their experiences.

IMHO, when therapy ends the transference stage, in most cases, it goes downhill from that point on, sorry for the gloomy forecast. Some people may have different experiences with this, so they might strongly disagree. I am just giving my perspective.