I let mine die down naturally for the first three years. This is so all the sugars and energy that the leaves create go to the roots to make the plant stronger for years to come.
After this time you can then pick the stalks as they grow and the plant will be strong enough to cope.

Same problem with asparagus.

Don't do anything with them, they will die back with the first frost. If you know when that is going to be you can pick any good stalks that day because they would be killed overnight anyway. Next year you can pick one or two stalks only, taking only one from each little centre, and only if the plant is growing vigorously. Just remember that picking too large a proportion will prevent the plant from maturing as fast as it otherwise would and will weaken it considerably.

Thank you both.x