How do I turn off the automatic indentation feature?

By default, the automatic indentation is not turned on. You must have configured Vim to do automatic indentation in either .vimrc or .gvimrc files. You can disable automatic indentation using either,

    :filetype indent off

or

    :set nocindent

Also, check the setting for the following options:

    :set autoindent?

    :set smartindent?

    :set indentexpr?