You are able to delete or mark lists as inactive from Admin > List Maintenance
This will display all of your available lists with some options for you to make changes:
The search bar will allow you to easily find a list by its name.
Lists can be selected by clicking the checkboxes on the righthand side and then you have the options to delete or deactivate the selected lists, this can be done in bulk or one by one.
There is a checkbox at the bottom of the screen which will allow you to see any inactive lists and you have the option to re-activate these if needed.