Please keep in mind that deleting a map is irreversible and will no be able to undelete the map once deleted.
In IRIS 1.2.1
You can delete a map in Iris by clicking on the EDIT button next to the map name, which will open up the edit modal allowing you to delete or change the map name.
In IRIS 1.2.2
If you would like to delete a map in Iris 1.2.2, click the delete icon in the same row as the map that you would like to delete.