If i delete a journey in "Allocate Checklists", its tasks are still available in "My Journeys"

I deleted a Journey in "Allocate Checklists" tab, then I went in "My journeys" and its tasks are still visible, I don't understand why because this seems to happen only in Production environment, in fact doing the same actions in test environment lets me remove definitely the journey and its own tasks.

I attach some screenshot of the related issue in production and test environment.

These are screenshots in test environment (where I deleted 1 journey):

Do you know what can I do in production environment in order to remove the tasks of the relative Journey deleted in advance?

Thank you all,