Remove token from the store.

    :param opts: Salt master config options
    :param tok: Token to remove
    :returns: Empty dict if successful. None if failed.

def rm_token(opts, tok):
    '''
    Remove token from the store.

    :param opts: Salt master config options
    :param tok: Token to remove
    :returns: Empty dict if successful. None if failed.
    '''
    redis_client = _redis_client(opts)
    if not redis_client:
        return
    try:
        redis_client.delete(tok)
        return {}
    except Exception as err:
        log.warning('Could not remove token %s: %s', tok, err)