biblatex: How to remove the comma before ed./eds.?

Since you did not provide a minimal example, I'm assuming the default numeric style.

EDIT: Minimal exampe changed to style autortitle & friends.

\documentclass{article}

\usepackage[style=authortitle-ibid]{biblatex}

\makeatletter
\renewbibmacro*{bbx:editor}[1]{%
  \ifboolexpr{
    test \ifuseeditor
    and
    not test {\ifnameundef{editor}}
  }
    {\usebibmacro{bbx:dashcheck}
       {\bibnamedash}
       {\printnames{editor}%
%   \setunit{\addcomma\space}% DELETED
    \setunit{\addspace}% ADDED
    \usebibmacro{bbx:savehash}}%
%     \usebibmacro{#1}% DELETED
     \printtext[parens]{\usebibmacro{#1}}% ADDED
     \clearname{editor}}
    {\global\undef\bbx@lasthash}}
\makeatother

\usepackage[super]{nth}
\AtBeginDocument{\renewcommand*{\mkbibordinal}[1]{\nth{#1}}}

\usepackage{filecontents}

\begin{filecontents}{\jobname.bib}
@collection{A01,
  editor = {Author, A.},
  year = {2001},
  title = {Alpha},
  edition = {3},
}
\end{filecontents}

\addbibresource{\jobname.bib}

\nocite{*}

\begin{document}

\printbibliography

\end{document}

With more recent versions of biblatex you only need

\DeclareDelimFormat{editortypedelim}{\addspace}

for the space between the editor name and "ed.". The same delimiter exists for translators

\DeclareDelimFormat{translatortypedelim}{\addspace}

You get the parentheses around "ed." and "trans." with

\DeclareFieldFormat{editortype}{\mkbibparens{#1}}
\DeclareFieldFormat{translatortype}{\mkbibparens{#1}}

There is no need to redefine bbx:editor.

In practice it is recommended (because it is less redundant) to use aliases for the translator

\documentclass[british]{article}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage{babel}
\usepackage{csquotes}

\usepackage[style=authoryear, backend=biber]{biblatex}

% (ed.)/(eds.) for editors
\DeclareDelimFormat{editortypedelim}{\addspace}
\DeclareFieldFormat{editortype}{\mkbibparens{#1}}

% same for (trans.)
\DeclareDelimAlias{translatortypedelim}{editortypedelim}
\DeclareFieldAlias{translatortype}{editortype}

\addbibresource{biblatex-examples.bib}

\begin{document}
\cite{vizedom:related,westfahl:frontier}
\printbibliography
\end{document}