Blocking a Student (advice)

I have a student who is making me uncomfortable in class, constantly flirting and being suggestive.Then this student becomes cold and uninterested in participating in the lesson if I hadn’t been receptive to their advances.

This student sent me their number in chat and is trying to get me to message them often. I’m worried that Preply will assume I asked for his number, or worse if I block him he will say I asked for his number for some reason.

I am just worried about doing something that will get me banned on Preply as I love working there and it’s my only source of income. I heard that you can be permanently banned for little reason and little explanation.

Any advice would be helpful. Also, this student has several lessons scheduled.

I was thinking of sending a message to the student saying something to the effect of “due to personal reasons I can not continue to be your tutor, and that all of your lessons can be transferred to a new tutor, I wish you luck on your English journey”.

But what should I say on the “reason for blocked” section, just want to make sure I cover myself.

Been feeling really uncomfortable with this student, thanks for your help!