How to unlink old MC account and link new one?

I need help unlinking my old Minecraft account from my forums account and linking my new one instead. I've been unable to find an option to do this myself, so I'm unsure if this is something where I'd have to seek help from the support team.

About three years ago, I had my rank transferred from my old account (Jasiyah) to my current account (jaskeei). However, Jasiyah is still linked to this forums account which I'd like to link jaskeei instead.

How does one go about requesting help regarding this? I'm just now getting back into Wynncraft and this just came to my attention.