Looks like Fatsia rather than true castor oil plant. Best not pruned now, at the start of winter, leave it alone and cut of anything you don't want around the end of May or in June.

THANKS FOR YOUR ADVICE WHICH LEAVES SHALL I CUT OFF WHEN PRUNING? SHOULD I TAKE OFF BOTTOM ONES O MAKE IT GROW TALLER

You don't have to prune it at all, it will reach about 8 to 10 feet all in its own, so unless you want to restrict its spread sideways, when you can remove some growths at the sides, don't prune