Switching from a Core billing plan to a Free Student billing plan

I’m currently paying for a Core plan on Webflow but I just discover than as a student I can have the same plan but for free. However I have already made and publish more than 2 sites which means I cannot downgrade to Starter and so, that I cannot switch back to core with the student discount.

Does anyone knows how can I switch to the free student plan without losing all my websites ?

thank you,