# enumerate with letters latex

\usepackage{enumitem}
...
\begin{enumerate}[label=\Alph*]
\item this is item a
\item another item
\end{enumerate}

or

[label=\alph*)]

Here is what the above code is Doing:
1. The first line is importing the package.
2. The second line is setting the label to be uppercase letters.
3. The third line is setting the label to be lowercase letters.