It seems that, from Google Cloud Console there is no way to delete a project.
Note: As of 2013-09-19 this is no longer an issue because Google had fixed
open cmd in google cloud(which can be found after clicking in your project in right top corner) and type
gcloud projects delete [..your-project-id..]
As 2017 approaches, Raptor's answer pretty much nailed it, but here is a screenshot and the basic steps to delete a project from the google cloud platform.
UPDATE 11-2020
After clicking SHUT DOWN, you'll see the final dialog popup with instructions on what to type to confirm.
Tty to change back to old console design.. You can find delete button there.
This is the old url https://code.google.com/apis/console/
Then you click in the left sidebar on the project name, you'll have a "delete" link :)
Deleting your project from old console is no longer available!
So in the new console go to Billing and Settings
and delete your project from there.
And you are done. Project will get deleted after 7 days waiting period!
It's July 2018, none of the above works. Here is what I spotted and successfully deleted un-needed projects.
https://cloud.google.com/go/getting-started/delete-tutorial-resources
You need to delete all the unwanted project(s) else will be billed regardless.
Step By Step to disable and request permanent deletion from Google Cloud Console and Google Appengine Project.
Step 1 - Navigate to appengine project and Click on Application Settings.
Step 2 - Scroll/Find the button to Disable Application. Click the button.
Step 3 - Click on "Disable Application Now"
Step 4 - Click on "Request Permanent Deletion". You will screen update showing the scheduled delete.
Step 5 - Navigate to Google Cloud Console. The status corresponding to the disabled/deleted project is shown as "Disabled" in red.