Once you have published the application, you can no longer edit the load script. You really wouldn't want to let developers/Users changing the load script with something that is in 'production'.
What you need to do is create a duplicate copy of the application into your 'My Work' area.
Once again, this is accomplished in QMC. Go the Apps screen in QMC and select the application. You can then duplicate and it will show up in your 'My Work' folder. Once there you can edit the app, test and then re-publish.
Support for deleting apps in My work from the Hub was added in Qlik Sense Enterprise 2.0 (if I remember it correctly). Since you are using 1.1, you will have to delete the app from QMC instead (as Kevin already mentioned).
Delete apps from the Hub when using Qlik Sense Desktop was however already supported in 1.1.