Header and footer modification in scrlayer-scrpage

Question

I'm using a template with master latex class document that defines the header and footer section. I want my head separation line to be orange and header itself without chapter or page number information. Here is the code:

\RequirePackage[markcase=used]{scrlayer-scrpage}
\providepairofpagestyles{thesisSimple}{%
\clearpairofpagestyles%
\automark[chapter]{chapter}
\ihead{\headmark}% Inner header
\ohead[\pagemark]{\pagemark}% Outer header
}
\ifoot{}% Inner footer
\ofoot{}% Outer footer
\pagestyle{thesisSimple}
\providepairofpagestyles[thesisSimple]{thesis}{%
\automark*[section]{}%
}
\providepairofpagestyles[thesisSimple]{review}{%
\ofoot[\shorttitle/\authorname]{\shorttitle/\authorname}
\ifoot[\today]{\today}
}
\pagestyle{thesis}
\ifbool{headsepline}{\KOMAoption{headsepline}{true}}{}
\PreventPackageFromLoading[\ClassError{\classname}{Package `fancyhdr' is
incompatible\MessageBreak with this class}{The pagesyles are defined 
using package `scrlayer-scrpage', please consult the\MessageBreak 
KOMA-script documentation for details.}]{fancyhdr}


\newcommand{\blank@p@gestyle}{empty}
\newcommand{\chapter@p@gestyle}{plain}
\NewDocumentCommand{\blankpagestyle}{ m }{%
\ClassWarning{\classname}{\string\blankpagestyle\space is
obsolete,\MessageBreak use \string\setblankpagestyle \space instead}\renewcommand{\blank@p@gestyle}{}{#1}
}
\NewDocumentCommand{\setblankpagestyle}{ m }{\renewcommand{\blank@p@gestyle}{#1}}
\NewDocumentCommand{\setchapterpagestyle}{ m }{\renewcommand{\chapter@p@gestyle}{#1}}

\DeclareDocumentCommand\cleardoublepage{}{\clearpage\if@twoside \ifodd\c@page\else
\hbox{}
\thispagestyle{\blank@p@gestyle}
\newpage
\if@twocolumn\hbox{}\newpage\fi\fi\fi%
}

Answer 1

Unfortunaly there is no MWE in the question and the OP does not say, if one or all page styles should be modified or if a new page style should be defined to get the empty header with an orange separation line.

To modify all layer page styles:

\AddToLayerPageStyleOptions{@everystyle@}
  {oninit=%
    \KOMAoptions{headsepline,plainheadsepline}\setkomafont{headsepline}{\color{orange}}%
    \ihead*{}\chead*{}\ohead*{}%
  }

To modify one layer page style including the related plain style, eg. thesisSimple:

\AddToLayerPageStyleOptions{thesisSimple}
  {oninit=%
    \KOMAoptions{headsepline}\setkomafont{headsepline}{\color{orange}}%
    \ihead{}\chead{}\ohead{}%
  }
\AddToLayerPageStyleOptions{plain.thesisSimple}
  {oninit=%
    \KOMAoptions{headsepline,plainheadsepline}\setkomafont{headsepline}{\color{orange}}%
    \ihead*{}\chead*{}\ohead*{}%
  }

Defining a new pair of layer page styles:

\providepairofpagestyles{myThesis}{%
  \clearpairofpagestyles
  \ifoot[\currentpagestyle: inner footer]{inner footer}
  \cfoot*{\pagemark}
  \ofoot[outer footer]{\currentpagestyle: outer footer}
}
\AddToLayerPageStyleOptions{myThesis}
  {oninit=\KOMAoptions{headsepline}\setkomafont{headsepline}{\color{orange}}}
\AddToLayerPageStyleOptions{plain.myThesis}
  {oninit=\KOMAoptions{headsepline,plainheadsepline}\setkomafont{headsepline}{\color{orange}}%
}

Example:

\documentclass{book}
\usepackage{xcolor}

\usepackage[markcase=used]{scrlayer-scrpage}
\providepairofpagestyles{thesisSimple}{%
\clearpairofpagestyles%
\automark[chapter]{chapter}
\ihead{\headmark}% Inner header
\ohead[\pagemark]{\pagemark}% Outer header
}
\ifoot{}% Inner footer
\ofoot{}% Outer footer
\pagestyle{thesisSimple}
\providepairofpagestyles[thesisSimple]{thesis}{%
\automark*[section]{}%
}
\providepairofpagestyles[thesisSimple]{review}{%
\ofoot[\shorttitle/\authorname]{\shorttitle/\authorname}
\ifoot[\today]{\today}
}
\pagestyle{thesis}

\newcommand*\shorttitle{Short Title}
\newcommand*\authorname{Author Name}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

%%%% modify all layer page styles:
\AddToLayerPageStyleOptions{@everystyle@}
  {oninit=%
    \KOMAoptions{headsepline,plainheadsepline}\setkomafont{headsepline}{\color{orange}}%
    \ihead*{}\chead*{}\ohead*{}%
  }
%%%%
% or
%%%% modify one layer page style and its plain style
%\AddToLayerPageStyleOptions{thesisSimple}
  %{oninit=%
    %\KOMAoptions{headsepline}\setkomafont{headsepline}{\color{orange}}%
    %\ihead{}\chead{}\ohead{}%
  %}
%\AddToLayerPageStyleOptions{plain.thesisSimple}
  %{oninit=%
    %\KOMAoptions{headsepline,plainheadsepline}\setkomafont{headsepline}{\color{orange}}%
    %\ihead*{}\chead*{}\ohead*{}%
  %}
%%%%
% or
%%%% new pair of layer page styles:
%\providepairofpagestyles{myThesis}{%
  %\clearpairofpagestyles
  %\ifoot[\currentpagestyle: inner footer]{inner footer}
  %\cfoot*{\pagemark}
  %\ofoot[outer footer]{\currentpagestyle: outer footer}
%}
%\AddToLayerPageStyleOptions{myThesis}
  %{oninit=\KOMAoptions{headsepline}\setkomafont{headsepline}{\color{orange}}}
%\AddToLayerPageStyleOptions{plain.myThesis}
  %{oninit=\KOMAoptions{headsepline,plainheadsepline}\setkomafont{headsepline}{\color{orange}}%
%}
%%%%

\usepackage{blindtext}% only for dummy text
\begin{document}
\blinddocument
\cleardoublepage
\pagestyle{thesisSimple}
\blinddocument
\IfLayerPageStyleExists{myThesis}{
  \cleardoublepage
  \pagestyle{myThesis}
  \blinddocument
}{}
\cleardoublepage
\pagestyle{review}
\blinddocument
\end{document}