Find the Exact Value of the Expression $\cot 45 ^ { \circ } - \sin 60 ^ { \circ }$

Multiple Choice

Find the exact value of the expression. Do not use a calculator.
- $\cot 45 ^ { \circ } - \sin 60 ^ { \circ }$

A) $\frac { 2 - \sqrt { 3 } } { 2 }$
B) $- \frac { \sqrt { 3 } } { 6 }$
C) $\frac { 2 - \sqrt { 2 } } { 2 }$
D) $\frac { 2 \sqrt { 3 } - 3 \sqrt { 2 } } { 6 }$