If your device still is showing an "almost full" iCloud storage, the images might be the reason. In that case, turning it off still wouldn't help, as they'd still be in iCloud for 30 days. Within that time, you'd have to download the images to your iPhone, if you don't want to lose them completely.
In any case, don't leave these images on your iPhone only. Save them to your computer, or load them to online storage, such as Google Photos, OneDrive or Flickr, if you don't want to lose them. As stated before, iCloud is used for syncing, not for storing photos.