Overwrite the macro with an empty box:
\renewcommand*\bibnamedash{\makebox[\leftmargin]{}}
or if you want to repeat the author name:
\usepackage[dashed=false,...]{biblatex}
And if it does not work than your bibstyle dowsn't support it. The style authoryear does it. For biblatex-chicago try:
...
\usepackage{biblatex-chicago}
\renewbibmacro*{author}{%
\ifboolexpr{
test \ifuseauthor
and
not test {\ifnameundef{author}}
}
{\printnames{author}%
\iffieldundef{authortype}
{\setunit{\addspace}}
{\setunit{\addcomma\space}}%
\iffieldundef{authortype}
{}
{\usebibmacro{authorstrg}%
\setunit{\addspace}}}%
{\global\undef\bbx@lasthash
\usebibmacro{labeltitle}%
\setunit*{\addspace}}%
\usebibmacro{date}}
...
which worked for me.