If you have rooted your Samsung Galaxy S4 and you want to disable over-the-air updates, you can try this:
- Open Root Explorer
- Navigate to /system/apps
- Rename SDM.apk to SDM.apk.old
- Rename SDM.odex to SDM.odex.old
This worked for me. However, if you have the paid version of Titanium Backup you can use Titanium Backup to freeze the SDM app.