Within an organization, you, as an organization owner or as a User with Manage user permissions can add or remove users on organizations and projects.
To add users to an organization:
1. Navigate to your existing organization or a project in it.
2. Open the user menu (your name or profile picture).
3. Click on Users.
4. Click on Invite users.
5. Enter the email address and grant the necessary permissions.
6. Send Invite (the user needs to accept the invitation).
To remove a user from organization:
Follow the previous steps, except that you will need to click on the user's three little dots and then click on Remove user from organization.
If you continue having questions, please do not hesitate to open a support ticket.