To solve for $\csc \left(-270^{\circ}\right)$, we need to understand the relationship between the cosecant function and the sine function. The cosecant function is the reciprocal of the sine function. Therefore, we first need to find $\sin \left(-270^{\circ}\right)$ and then take its reciprocal.
Step 1: Convert Degrees to Radians
To find \(\csc \left(-270^{\circ}\right)\), we first convert the angle from degrees to radians:
\[
-270^{\circ} = -\frac{3\pi}{2} \text{ radians}
\]
The cosecant function is the reciprocal of the sine function:
\[
\csc \left(-\frac{3\pi}{2}\right) = \frac{1}{\sin \left(-\frac{3\pi}{2}\right)} = \frac{1}{1} = 1
\]