I don't know about katuk, but moringa can be pruned at any height. If growing from seed, it's good to start pruning by 3rd or 4th branching (cut the tips) to encourage more branching. If they are tall ~5', you can chop them down to 2' and they'll come right back. That's how my family and others I know did/do it anyway. I had a 3" sapling which the cabbage worms ate the tiny leaves, leaving a bare trunk. I was bummed to see. BUT no problems though, it threw out two branches. Moringa are robust plants. Let us know how it goes. Here's video I just found that says exactly what I told you:
https://youtu.be/WaR31jsAfA8