Don't know which phone you have but one of the main Culprits on my phone that adds new apps without you knowing it is DT Ignite. At least we can disable this app so it doesn't add anymore junk apps to our phone. Another thing you can do is before you disable a app is to go into storage on the app and clear the clear data. You would be surprised how much data is stored in the apps. If you cleared the cached data out from the internal storage that would clear a lot out also but the one that will give you a lot more room is the cache partition that is in the recovery mode on your phone. On a samsung phone you turn the phone off then hold Volume up-power-home. That will take you into recovery mode then just use the volume down key to clear cache partition press power then use the volume down key to say yes then power again. Then just reboot the phone. This will not mess up any of the settings on the phone. It just clears out a lot of old files that are dumped there by updates and other things that your phone doesn't need anymore.