Archiving is the best option you have if you need to keep your sidebar organised but are not ready to delete the projects you have created. All tasks under the archived projects remain on the timeline in teams view. Every archived project can be unarchived.
To archive a project:
- Click on the three dot menu on the top right corner or after the project name on the sidebar
- Click on "Archive"
Archived projects can be accessed on the sidebar. To visit the project timeline, the project needs to be unarchived. It can be done on clicking on the button "Unarchive" in the Archived folder.