rename or remove original shopify-managed subdomain

i saw that we need to contact support in order to do this, but i can’t figure out how to actually contact support — all visible links seem to redirect me to these forums !

You can try using this direct link to reach out to support
https://help.shopify.com/en/questions#/contact/
If the link keeps redirecting to the home page, try opening the link in Chrome Incognito mode.

Alternatively, I’ve recorded a video showing a step-by-step process of how to reach support.
https://www.youtube.com/watch?v=6Dh3jkf7Xas