How do you get rid of it
I assume the only way to get rid of iris with round up??
If you do not want to use a chemical herbicide, you could dig it up. You didn't say what kind of iris you have but perhaps a garden club who is having a plant sale may accept donations of potted up plants. But as a general rule of thumb for unwanted plants your options are an herbicide, digging them up or in some cases cutting them very close to the ground and putting several layers of cardboard or black plastic topped with mulch over them. This latter technique would probably work with Siberian or Japanese or German bearded irises but would take a couple of months to smother them.