How to Prune English iris?
No pruning required, Remove the foliage once it has died down

English iris · Iris latifolia
Also known as: great bulbous iris; Pyrenean flag
Grow in moist but well-drained neutral or slightly alkaline soil, preferably in a sunny spot where the soil does not dry out. See bulb iris cultivation for further advice. May be naturalised in grass
No pruning required, Remove the foliage once it has died down