To be able to edit the project details you have to be the owner/creator of the project. First, go to your project list and click the project you want to edit.
This opens up the project details screen.
Click the corresponding buttons to change the following project details: Name, Description and Image.
You can invite or remove participants by clicking Share Board. For more details on how to do this, see: I want to invite a friend to participate in a project, how do I do that?
Clicking the Cancel Project will revoke all added participants to the project and delete it. Only the project creator can do this. If you are not the creator of the project this button will read Leave Project. Pressing it will remove your access to the project and thus remove it from your list of projects.