What you own
Your organization owns the Cloudflare, GitHub, and Sanity accounts. Everbase is granted access and is not the account owner.
The Everbase Stack is Astro or Next.js, with Sanity, on Cloudflare or Vercel. After handover the marketing site runs on The Everbase Stack, in accounts your organization owns.
The accounts
You own Cloudflare, where the site is hosted. You own GitHub, where the code lives. You own Sanity, where editors change content. Everbase is invited in. Everbase does not own the accounts, and nobody shares a login to grant that access.
The accounts list in your handover doc names every account, the owner, the access Everbase still has, and when to remove it.
The repository
The repository is in your GitHub organization. It includes the docs for how the site is run and the checks that have to pass before a change lands. Content edits that Studio already allows do not need a code change.
What Everbase keeps
Everbase does not keep the host, the CMS, or the code. What Everbase keeps, while you want it, is access you granted and, if you choose it, Continuous development. Both are reversible. How to remove them is on How to leave.