Can you separate hibiscus plants?
Can You Separate Hibiscus Plants
Certified GKH Gardening Expert
Unless they are "growing" by putting out suckers (stems from the ground), you cannot divide them. You would be better off pruning to control their size, should overgrowth be the case. This article will help with that:
If you are simply wanting to produce more plants, this article will help: https://www.gardeningknowhow.com/ornamental/flowers/hibiscus/hibiscus-propagation.htm