title: removing slide numbers in r markdown
body: <p>How can I remove slide numbers from Rmarkdown beamer presentation using a 'madrid' theme.
  Additionally how can I specify or increase the font size</p>
  
  <pre><code>---
  title: "Title"
  author: "Keniajin"
  output:
    beamer_presentation:
      theme: "Madrid"
      colortheme: "default" 
      fonttheme: "professionalfonts"
  header-includes:
  - \usepackage{booktabs}
  - \usepackage{longtable}
  - \usepackage{array}
  - \usepackage{multirow}
  - \usepackage{wrapfig}
  - \usepackage{float}
  - \usepackage{colortbl}
  - \usepackage{pdflscape}
  - \usepackage{tabu}
  - \usepackage{xcolor}
  - \usepackage{threeparttable}
  - \newcommand{\columnsbegin}{\begin{columns}}
  - \newcommand{\columnsend}{\end{columns}}
  - \newenvironment{knitrout}{\setlength{\topsep}{0mm}}{}
  fontsize: 30pt
  ---
  
  ## Background
  
  This is background
  
  ## Histrory
  
  Hii story ya
  
  ## Methods
  
  ### Method A - about this
  </code></pre>
  
  <p>I tried using <code>\setbeamertemplate{page number in head/foot}{}</code> and it was not successful.</p>