We can remove the accountant through the Manage Users page, xerky.

Let me guide you with these steps:

1. Click the Gear icon and then select Manage users.
2. Go to the Accountants tab.
3. Locate the accountant's name and click Delete under ACTION.
4. Click Yes to confirm.

Once deleted, you're good to add a new one. 

You can also share this reference to your new accountant that has lists on what they can do with your QuickBooks account: Use accountant tools and features in QuickBooks Online Accountant.

As always, I'm just a post-away if you need help. Keep safe!