[git] How can I delete a file from a Git repository?

More generally, git help will help with at least simple questions like this:

zhasper@berens:/media/Kindle/documents$ git help
usage: git [--version] [--exec-path[=GIT_EXEC_PATH]] [--html-path] [-p|--paginate|--no-pager] [--bare] [--git-dir=GIT_DIR] [--work-tree=GIT_WORK_TREE] [--help] COMMAND [ARGS]

The most commonly used git commands are:
   add        Add file contents to the index
   :
   rm         Remove files from the working tree and from the index