You have several options:
- in enviroment / options / editor / general: disable "auto indent"
and in codetools general (0.9.29) is indentation too.
But they are both either always or never
- you can place the caret at the leftmost pos (pos 1) of the lower line, before pressing return, then it moves the line down without indent. But you need to move back up
- You can insert a new line with ctrl-n, then no indent happens, but the caret stays where it is.