Once a project is added, it is reflected across all your dashboards; which includes the Site Explorer, Rank Tracker and Site Audit. So it is important to keep in mind that deleting a project from one dashboard, will in fact remove the project from the other two.
Before proceeding, ensure that the projects you are deleting do not have data being tracked on the other dashboards that is still needed.
Note: The "Hide" option is best if you do not want to delete a project from one dashboard that has data being tracked on another dashboard. For example: If you create a project in Site Audit, but do not want to track keywords for that project in the Rank Tracker or see it reflected on the Site Explorer dashboard; that project can be hidden on the Rank Tracker and Site Explorer dashboards.
Now onto the guide for deleting or hiding your project. See below:
Scroll to the project you would like to delete or hide; then inline with this project, click on the menu (vertical 3 dots):
2. Select "Settings" from the drop-down to see the "Delete project" option:
To Hide the project, simply click "Hide" from the options: