How do you make your 7 year old girl cousin shutup?

ok this is my question and she is annoying me all day and im 13 and shes 7 and her moms a and she never takes any side but hers so i have no chance and she gets everything she likes so my idea is to pick her up knock her out and carry her 5 miles Into the Woods and strap her to a tree and leave her. P.S. im seriously considering it