Solve the Equation: -|15| = Finding the Negative Absolute Value

To solve the given expression $-\left|15\right|$, we need to find the absolute value of $15$, then apply the negative sign.

The absolute value of a number is the non-negative value of that number without regard to its sign.

Thus, $\left|15\right| = 15$.

Now apply the negative sign: $-\left|15\right| = -15$.

Therefore, the answer is $-15$.