How to remove the word "Notes" from usepackage{endnote}?

You can use renewcommand*{enoteheading}{} to remove the heading completely.

Example:

documentclass{article}
usepackage{endnotes}
renewcommand*{enoteheading}{}% removes the heading comletely
begin{document}

textendnote{test footnote}

theendnotes
end{document}

If only text »Notes« (but not the vertical space) should be reomved (or replaced), redefine notesname.

Example:

documentclass{article}
usepackage{endnotes}
renewcommand*{notesname}{}% removes only the name 
begin{document}

textendnote{test footnote}

theendnotes
end{document}

I'm a beginner latex user, thus no expert at all. But yet, I found a solution by adding defnotesname{relax} in the definitions of the endnotes.