You can either delete or archive projects. We recommend first considering archiving your project because deleting is a far more permanent solution as it can't be undone. The advantage to deleting your project is that the files no longer count towards your file storage limit. Unless you're reaching your file storage limit archiving your project makes more sense in most cases.
Before deleting your project make sure you've exported all the data from the project that you want..
In order to delete a project, go to the project you want to delete and click the project settings gear.
Next go to the "Delete Project" page in the sidebar.
Lastly read through this page and if you decide to delete your project select the checkbox to confirm you want to delete the project and then click the "Delete Project" button.