To remove a user, you will need to visit the User list page in Company Settings.
As an Administrator, go to Settings > Company Settings > Users. Select the User(s) to remove then click Actions > Remove user. You will be asked to confirm the removal:
The user(s) will no longer have access to this company account or its documents. Remember to share the documents with appropriate users and/or administrators before deleting any account. The Administrator Access setting can also be activated to ensure that Administrators have an overview of all documents on the account even after the user is removed.
The user(s) will still have access to any other companies they joined or created, along with the company's corresponding documents.
Note: It is also possible to remove users that have not yet replied to an invitation (status = Pending invitation) this way. The invitation will be voided in that case.
Removing users does not update the seats in your subscription. If you have a paid account, you will need to update seats from the seats management page in order for the changes to be reflected in the invoice.