I have installed Delete my account plugin into Joomla 3.6.0 and it works fine.
According the documentation, it should be possible to change the text of html which is displayed to user.
But I did not find any language file like en-Gb.plg_system_f990deletemyaccount.ini to override.
Everything is ok.
I finally found the file in my directory ..\joomla-3.6.0-1\apps\joomla\htdocs\administrator\language\en-GB\
For whatever reasont I could not find it yesterday on my computer. It was just after install so maybe my file explorer was not up to date.