reduce space at the top using maketitle

Include the \vspace command in the title command, i.e. change the line

\title{Title}

into

\title{\vspace{-2cm}Title}

The titling package can help you in this.

From its documentation:

The ti­tling pack­age pro­vides con­trol over the type­set­ting of the \maketi­tle com­mand

In your case, adding these lines in the preamble (adjust -3cm to your needs) should do what you want:

\usepackage{titling}
\setlength{\droptitle}{-3cm}

Have a look at the documentation for more options (e.g. spacing after the title)