hi, hope someone can help

we have a NZ Flax the size of Birmingham in our garden, and we would like to move it to a better location as it is really in the way. We really like the plant, and dont want to lose it when we move it. What would be the best way to do it? Also the flower stalk must be 10ft tall, we know it flowers in summer, but should we cut it down after it has flowered or should it die down naturally? We have been in this house since September and it hasnt died down yet.

Any advice would be appreciated, thanks