Guidance on Setting Up an Existing Project on Free Plan with New UI

I'm trying to set up an existing project on a Free plan, to give some people access that aren't allowed access to other project on our Professional account. With the new UI, it seems impossible to delete the project that is automatically created, and therefore impossible to import an existing project into the free account. This used to be easily possible in the old UI, can you guide me through this? This issue also makes it impossible to use any Template for a project in the free account by the way.