Want to cancel student sign up but cannot find anywhere to do so

Did you sign up via a colledge provided offer, or did you sign up for a personal studend licence directly from the Adobe webstite?

If the first is the case: you need to contact your college.

If the second is the case: Go to https://account.adobe.com/plans, click "manage plan" and cancel. The refund will be processed after that, but may take up to 10 days to be credited. If you have trouble with that, proceed as @kglad indicated.

use a browser that allows popups and cookies and contact adobe support by clicking here, https://helpx.adobe.com/contact.html?rghtup=autoOpen
in the chat field (lower right), type AGENT
be patient, it can take quite a while to reach a human

p.s you can also use phone (but chat is usually quicker), https://helpx.adobe.com/contact/phone.html

p.p.s. you can also use twitter to tweet @AdobeCare

p.p.p.s. if you're contacted by anyone (via email or private message), it's much more likely to be a scammer than an adobe representative. ie, double check for an employee badge if contacted in the forums and look for an adobe.com domain in the email address if you click reply to an email. then check again and be very suspicious. any other method of contacting (or offering to contact you) is almost certainly a scam, https://community.adobe.com/t5/using-the-community-discussions/staying-safe-in-the-adobe-support-community/td-p/12919684/redirect_from_archived_page/true