clearState

Clears the application state:

- clearState            # clears the state of the current app
- clearState: app.id    # clears the state of an arbitrary app

What is being cleared?

Android

The outcome of the command is identical to:

adb shell pm clear {package name}

That is removing all app-related data from the device (shared preferences, databases, accounts, etc.)

iOS

The command is removing the contents of the application's data folder. An equivalent idb command would be:

idb file rm --application {bundle id}/

It's also possible to use xcrun simctl for that.