Just so you know, deleting a project will permanently delete all the time entries related to it. The action is not reversible.
You can delete a project from the Project view. Please note that before you can delete it, you need to archive the project first.
Go to Projects;
Use the filters to select the archived projects;
Select the project you want to delete;
Select DELETE.
Please note that deleting a project is a permanent operation and cannot be undone, that also deletes the project's entries as well.