If your plant is healthy and you want more blooms. Then either let it be or cut it above the 3rd or 4th node. Either way you do it. It wont matter.The plant will decide to rebloom, set keiki, or the spike will die off. Otherwise if you dont have a healthy plant, lack of roots and leaves. Then just cut off the whole spike off so the plant can redirect energy to new growth. This is assuming that your talking about a Phalaenopsis. Hope this helps.