Answer
$csch \theta \text{coth} \theta (\ln csch \theta)$
Work Step by Step
Given: $y=csch \theta (1-\ln csch \theta)$
Since, $\dfrac{d}{dx} (csch x)=\text{-csch} x \text{coth} x$
Thus,
$\dfrac{dy}{d \theta}=csch \theta[\dfrac{-1}{csch \theta}( -csch \theta coth \theta)]+(1-\ln csch \theta)$
or, $=(csch \theta coth \theta)[1-(1-\ln csch \theta)]$
or, $=csch \theta \text{coth} \theta (\ln csch \theta)$
