These white, lush lilies might look innocent enough, but their large leaves can kill off surrounding plants. In locations that don’t experience freezing weather, calla lilies spread like wild fire and will block the sun from hitting other plants. It doesn’t take much for a new plant to sprout, so it’s best to stay on top of new shoots or keep these lilies in containers. Calla lilies, native to South Africa, are considered an invasive species in some areas of the U.S. They spread by bird-borne seed and by pieces of rhizome in garden soil and by cuttings. It is best to remove flowers as they fade to decrease the amount of seed available to birds and dispose of rhizomes and plant cuttings responsibly.

• Cannas usually need to be divided once every two to three years, but crowded conditions and reduced plant vigor are good indications that it is time to divide and control the canna lilies.
• Without dividing the cannas regularly, the rhizomes can spread to unwanted areas of the garden and overtake smaller accent plants.
• If you want to get rid of the cannas altogether, simply dig up all the rhizomes and discard them, rather than dividing and replanting them.

https://www.gardeningknowhow.com/ornamental/bulbs/calla-lily/dividing-calla-lilies.htm/?print=1&loc=bot

Hope this helps!