I want to be able to delete the images off my phone but keep them in iCloud, how do i do this?

Apple does not offer any cloud-only storage options. If you delete a photo from any device that is using iCloud Photo Library it will be deleted from iCloud and from all other devices that are connected to that iCloud Photo Library. If you want to request more storage options for the future, the following link may help: http://www.apple.com/feedback/icloud.html

There are 3rd party options that offer cloud-only storage including Dropbox and Flickr.

Google Drive is really awesome for online storage too it has 20 GB of space and you can keep it just in the drive and not have to have it on your phone, Plus it makes it much easier if you ever do switch to an android device, I have both my android and my iPhone and it makes it easy to share pictures, videos, documents, contacts, and music.