title: command line; delete static file in a folders who begins with certain character
body: <p>I have hundreds of folders like 
  170102texta
  170204textb
  180306textc
  180408textd</p>
  
  <p>these folders and many subfolder is the file test.txt present. 
  I would like to to delete all the "test.txt" files but only in the folders who begins with "17.."</p>
  
  <p>every advice is appreciated :)</p>