I have stared at the UI for my sonarlcloud.io projects for a while now, but cannot for the life of me see how to delete a project from analysis. How&where do I do that? Is it from GitHub, is it from the sonar cloud web page or what?
You need to be browsing a SonarCloud project (click into the projects displayed on the screen you shared). If you have Administer access on the project, you will see the Administration menu.