How to Prune golden rat tail?
No pruning required

golden rat tail · Cleistocactus winteri
Also known as: gold-spined hildewintera; gold-spined winterocereus
Under glass, grow in standard cactus compost in full light and with low humidity. In the growing season water moderately and apply a dilute low-nitrogen fertiliser monthly. Keep completely dry from mid-autumn to spring. See houseplant cacti and succulent cultivation for further information
No pruning required