CAREFREE
(as) free as a bird
carefree; completely free.Jane left home and is always happy and free as a bird.In the summer I feel free as a bird.
devil-may-care attitude and devil-may-care manner
a very casual attitude; a worry-free or carefree attitude.You must get rid of your devil-may-care attitude if you want to succeed.She acts so thoughtless with her devil-may-care manner.
footloose and fancy-free
without responsibilities or commitments. (Fixed order.)All the rest of them have wives, but John is footloose and fancy-free.Mary never stays long in any job. She likes being footloose and fancy-free.
not have a care in the world
free and casual; unworried and carefree.I really feel good today—as if I didn't have a care in the world.Ann always acts as if she doesn't have a care in the world.