$-2{y}^{5}+{y}^{3}-2y-\left( {y}^{5}-4{y}^{3}+6 \right)$
When there is a $-$ in front of an expression in parentheses, change the sign of each term of the expression and remove the parentheses$-2{y}^{5}+{y}^{3}-2y-{y}^{5}+4{y}^{3}-6$
Collect like terms$-3{y}^{5}+{y}^{3}-2y+4{y}^{3}-6$
Collect like terms$-3{y}^{5}+5{y}^{3}-2y-6$