You need to patch the command \makehead in file moderncvheadiii.sty. At the end it contains the code
\flushmakeheaddetails}\fi}\\[2.5em]}
and \\[2.5em] is responsible for the white space you do not like. Use the following patch in your preamble
\usepackage{etoolbox} % <===============================================
\patchcmd{\makehead}{\\[2.5em]}{\\[0em]}{}{} % <========================
Change the value 0em for your needs ...
Please see the following complete MWE:
\documentclass[11pt,a4paper,sans]{moderncv}
\moderncvstyle{banking}
\moderncvcolor{purple}
\usepackage[utf8]{inputenc}
\usepackage[scale=0.915]{geometry}
\usepackage{import}
\usepackage{etoolbox} % <===============================================
\patchcmd{\makehead}{\[2.5em]}{\[0em]}{}{} % <========================
\name{Name}{}
\phone[mobile]{ph}
\email{email@gmail.com}
\homepage{www.linkedin.com/in/profile}
\begin{document}
\maketitle
\section{Education}
\vspace{0pt}
\begin{itemize} % <=====================================================
\item \cventry{Expected Graduation: June 2022}{Bachelors in engineering}{Name of the university}{location}{\textit{}}{}
\end{itemize} % <=======================================================
\vspace{1pt}
\end{document}
You are using an \item without using \begin{itemize} and \end{itemize} in your code. That gives an error messages I corrected with adding \begin{itemize} and \end{itemize} to the MWE. Please see that command \item takes no parameter!
Now you have an paragraph going outside the rule as you can see in this screen shot:

In my answer to question moderncv extend hrule you can find the code to correct this error.