Can i cut my yucca trees down and plant them elswhere in the back yard

Yes you can, just don't pull them out of the ground, dig around them and deep enough to keep most of the roots intact. Dig the holes where you want to replant them first before digging the yuccas out!!! Once you have your plant dug out replant it in the new hole as soon as possible, use some good potting soil to fill around it and water it.. Yuccas are very tough plants so you should be OK.