The synthetic division table is:
$$ \begin{array}{c|rrr}-6&1&0&-36\\& & -6& \color{black}{36} \\ \hline &\color{blue}{1}&\color{blue}{-6}&\color{orangered}{0} \end{array} $$The solution is:
$$ \frac{ x^{2}-36 }{ x+6 } = \color{blue}{x-6} $$Step 1 : Write down the coefficients of the dividend into division table. Put the zero from $ x + 6 = 0 $ ( $ x = \color{blue}{ -6 } $ ) at the left.
$$ \begin{array}{c|rrr}\color{blue}{-6}&1&0&-36\\& & & \\ \hline &&& \end{array} $$Step 1 : Bring down the leading coefficient to the bottom row.
$$ \begin{array}{c|rrr}-6&\color{orangered}{ 1 }&0&-36\\& & & \\ \hline &\color{orangered}{1}&& \end{array} $$Step 2 : Multiply by the number on the left, and carry the result into the next column: $ \color{blue}{ -6 } \cdot \color{blue}{ 1 } = \color{blue}{ -6 } $.
$$ \begin{array}{c|rrr}\color{blue}{-6}&1&0&-36\\& & \color{blue}{-6} & \\ \hline &\color{blue}{1}&& \end{array} $$Step 3 : Add down last column: $ \color{orangered}{ 0 } + \color{orangered}{ \left( -6 \right) } = \color{orangered}{ -6 } $
$$ \begin{array}{c|rrr}-6&1&\color{orangered}{ 0 }&-36\\& & \color{orangered}{-6} & \\ \hline &1&\color{orangered}{-6}& \end{array} $$Step 4 : Multiply by the number on the left, and carry the result into the next column: $ \color{blue}{ -6 } \cdot \color{blue}{ \left( -6 \right) } = \color{blue}{ 36 } $.
$$ \begin{array}{c|rrr}\color{blue}{-6}&1&0&-36\\& & -6& \color{blue}{36} \\ \hline &1&\color{blue}{-6}& \end{array} $$Step 5 : Add down last column: $ \color{orangered}{ -36 } + \color{orangered}{ 36 } = \color{orangered}{ 0 } $
$$ \begin{array}{c|rrr}-6&1&0&\color{orangered}{ -36 }\\& & -6& \color{orangered}{36} \\ \hline &\color{blue}{1}&\color{blue}{-6}&\color{orangered}{0} \end{array} $$Bottom line represents the quotient $ \color{blue}{ x-6 } $ with a remainder of $ \color{red}{ 0 } $.