How to remove headrule in chapter page without remove of footrule, eg, rule only in foot page in all pages, but without on chapter page, but headrule in others pages.
\documentclass[a4paper]{memoir}
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\copypagestyle{rgstyle}{headings}
\makeoddhead{rgstyle}{}{}{\slshape\rightmark}
\makeevenhead{rgstyle}{\slshape\leftmark}{}{}
\makeoddfoot{rgstyle}{R\'egis $\smiley$ \the\year}{}{\thepage}
\makeevenfoot{rgstyle}{\thepage}{}{R\'egis $\smiley$ \the\year}
% add line
\makeheadrule{headings}{\textwidth}{\normalrulethickness}
\makefootrule{headings}{\textwidth}{\normalrulethickness}{\footruleskip}
% fix plain
\copypagestyle{plain}{rgstyle} % overwrite plain with rgstyle
\makeoddhead{plain}{}{}{} % remove right header
\makeevenhead{plain}{}{}{} % remove left header
\pagestyle{rgstyle}
\begin{document}
\chapter{Memoir without headrule in chapter page}
\lipsum
\end{document}


\chapteruse thechapterpagestyle, which is an alias forplain. I suggest making two pagestyles. One to use for regular pages, and one (without the headrule) which thechapterstyle can be aliased to. Only edit theplainstyle if you really know what you are doing. – daleif Dec 19 '11 at 12:56