How do I remove alphabetical grouping of acronyms in the list?

Heiko's answer works perfectly in your case, since you are printing only one glossary.

In fact, adding nogroupskip option at loading time, you change the behavior globally, i.e. for all glossaries.

Just in case you need to define it locally to one glossary, you can define a new style that redefines just that aspect:

\newglossarystyle{modsuper}{%
  \glossarystyle{super}%
  \renewcommand{\glsgroupskip}{}
}

and at printing time use

\printglossary[style=modsuper, type=\acronymtype]

The result is the same, but if you want to define another glossary where you want the gap between groups, this solution may be of interest.

MWE

\documentclass[11pt,a4paper,openany,oneside]{book}

\usepackage[acronym,nonumberlist,toc]{glossaries}
\usepackage{glossary-superragged}
\newglossarystyle{modsuper}{%
  \glossarystyle{super}%
  \renewcommand{\glsgroupskip}{}
}
\makeglossaries

\renewcommand*{\acronymname}{List of Acronyms and Abbreviations}
\renewcommand*{\glspostdescription}{} % remove trailing dot
\renewcommand{\glsnamefont}[1]{\textbf{#1}}
\newacronym[longplural={Affinity Diagrams}]{ad}{AD}{Affinity Diagram}
\newacronym{dom}{DOM}{Document Object Model}
\newacronym{svg}{SVG}{Scalable Vector Graphics}
\newacronym{spa}{SPA}{Single Page Application}

\begin{document}

\tableofcontents
\printglossary[style=modsuper, type=\acronymtype]

\section{First section}

Here we go... \gls{ad}, \gls{dom}, \gls{svg} and \gls{spa}!
\end{document} 

Output

Addendum

If you want to add some vertical space between items, you can define the new style as:

\newglossarystyle{modsuper}{%
  \glossarystyle{super}%
  \renewcommand{\glsgroupskip}{}%
  \renewcommand*{\glossaryentryfield}[5]{%
    \glsentryitem{##1}\glstarget{##1}{##2} & ##3\glspostdescription\space ##5\\[5pt]}%
}

and adjust 5pt to whatever you like. In this case the output will be:

The vertical gap between is controlled by option nogroupskip. From the user manual of package glossaries:

nogroupskip This is a boolean option. If no value is specified, true is assumed. When set to true, this option suppresses the default vertical gap between groups used by some of the predefined styles. The default setting is nogroupskip=false.

Also note the nopostdot option instead of the manual command.

Example file:

\documentclass[11pt,a4paper,openany,oneside]{book}

\usepackage[acronym,nonumberlist,toc,nogroupskip,nopostdot]{glossaries}
\usepackage{glossary-superragged}
\makeglossaries

\renewcommand*{\acronymname}{List of Acronyms and Abbreviations}
\renewcommand{\glsnamefont}[1]{\textbf{#1}}
\newacronym[longplural={Affinity Diagrams}]{ad}{AD}{Affinity Diagram}
\newacronym{dom}{DOM}{Document Object Model}
\newacronym{svg}{SVG}{Scalable Vector Graphics}
\newacronym{spa}{SPA}{Single Page Application}

\begin{document}

\tableofcontents
\printglossary[style=super, type=\acronymtype]

\section{First section}

Here we go... \gls{ad}, \gls{dom}, \gls{svg} and \gls{spa}!
\end{document}