Immediate joining
If Bob want to invite Alice to collaborate on his project, and Alice is already registered and has verified her email, Bob can just add Alice's email into the list of collaborators. Access will be granted immediately (page refresh may be required for Alice), although Alice will still get a notification email.
Immediate leaving
If Alice no more wants to collaborate in Bob's project, she can select the project in the "Shared Projects" section in the dashboard and leave it using Trash icon in the right pane.
