To stop the auto indenting (which puts in a tab as well):
Within the top-most menu:
Click on "Settings", within the submenu click on "Preferences"
Within the left portion of the Preferences popup, select "Auto-Completion" On the right side, outside the of the Auto-Completion box, Uncheck "Auto-Indent"
Click "Close" Note: This is for Notepad++ version 8.6