How do I reset the 2 system env variables NHOSTADMINSECRET and NHOSTWEBHOOKSECRET ?

It's not possible right now. You can upvote this issue where it's tracked: https://github.com/nhost/nhost/issues/400

If I generate a new variable and assign it under "project env variables" using the same name, can it override the system env variable everywhere?

No, it's not possible. Sorry

Oh. Is there workaround for it? It will only be a one-time action.

We can do it manually

Can you please write an email to me with the account you use at Nhost? Include the subdomain and what you want me to rotate

You can send it to johan@nhost.io

Ok. Thanks!

Actually, I would like to hold off on this action until I am further into my prod development in case the same event happens again during dev. Thanks.

Hopefully by that time you can do this action in the dashboard.