Seriously? After hours you didn't find "edit suquestions" and "edit answer options" in the top bar navigation of your question? I am not a big fan of the UI changes, but after "hours" you should be able to find that...
What do you mean with LS online? LS is a online survey tool, so it must be online somehow. Are you referring to the hosting provided by the Limesurvey GmbH? I have no idea how their backend is setup, but it seems like there has been some change recently, because I can't find this setting in the global settings of LS anymore. So maybe finally this has been made something that can not be fixed by the super admin, but by default can be chosen by each survey admin on a per survey basis.
go to the survey in question, then "survey properties" -> "Presentation & navigation" --> set "Show "No answer":" to "no".