A project w/o VMs, it is possible to right click on the project in the VM navigation tree, the delete option isn't grayed out, and the user got a pop-up window with the following prompt:

Are you sure you want to delete 0 Virtual Machines in 0 namespaces?
If you click the hyperlink an empty pop up window appear
clicking on the Delete button results in no-op

4.19.0

100%

1. In the VM navigation turn off the option to show projects only with VMs so it will show you all the projects. 
2. Create a an empty project.
3. Right click on the project and click on the delete option

Pop up window that asks if we want to delete 0 VMs from 0 NSs

Delete option to be grayed out