From the web browser:
- Select the "People" tab on the left column
- Select the person that you want to edit
- Select the "Permissions" tab at the top
- To give someone all administrative permissions, enable the first checkbox as shown below.
- You can deselect the 'has billing permissions' option if you want to allow all access except billing.
- You can also choose to only select certain workspaces and/or projects for limited access.
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To remove the person completely from the team, click on the link at the bottom: