Does assets being saved\deleted between application updates on mobile device?

Let's say i have deployed a game to iOS\Android app store and a client installs the app which weights 30 MB and the Unity project assets are : 2 scenes, 10 textures.

I have made some changes to the app and deleted 5 textures and a scene now the app build is about 20 MB and the Unity project assets are : 1 scene, 5 textures.

I have uploaded the new app build to the app store and the client downloaded the app update.

1. Does the app still contains the assets i have deleted ?
2. Now the app weight 20 MB instead of 30 MB on the client device ?

I'm asking this because in my project i have assets that are for testing purposes and i'm not sure if i should remove any assets that maybe are not going into the final build.

 

A new version of the client completely replaces the older version of the client.

 

Thanks zombiegorilla, wasn't sure about that.