Q.cutting yucca
Can I cut out the top center of a yucca to control height? Mine are nearly 3 metres tall and I don’t want them any higher and don’t want to hurt the plant.

Unfortunately cutting the top off of a Yucca will backfire and actually send the plant into grow mode! It will compensate by sending out LOTS of pups.
You can trim away dead and damaged leaves for a better appearance.
Here are some links for you.
https://www.gardeningknowhow.com/ornamental/foliage/yucca/caring-for-and-landscaping-with-yuccas-outdoors.htm
https://www.gardeningknowhow.com/ornamental/foliage/yucca/removing-yucca.htm