title: Clean minibuffer during file find in ido mode
body: <p>I use <code>C-a,C-k</code> to clean minibuffer when searching for a file in normal emacs. In ido mode, this key is bound to deleting a file. </p>
  
  <p>So, in ido mode, after going deep down the folder hierarchy, how to clean minibuffer and restart my file selection from root folder.</p>
  
  <p>Yes, i can use backspace to go up one step at a time, but that is tedious....</p>