How to withdraw authorization from a collaborator?

In order to withdraw the authorisation you've created to one of your collaborators, you need to:

1. Access your series
2. On the left panel, click on Series > Share with a colleague
3. In the table that summaries the people who can see your series, identify the collaborator you want to withdraw the access and click on the Remove button

That's it! The user can't access your series anymore.