With Xcode 6.1, to uninstall an app, use the following command:

xcrun simctl uninstall booted com.example.apple-samplecode.UICatalog

where com.example.apple-samplecode.UICatalog is the bundle identifier of the application you wish to uninstall.

One approach that we found for deleting user defaults is to delete all files in the ./data/Library/Preferences/* in addition to deleting application and data directories.

However, in Xcode 6, the command xcrun has new subcommand called simctl that allows me to manage iOS Simulator including resetting the simulator, and installing the application.

The solution that I came up with is to use the command

xcrun simctl erase [device ID]

Example

If xcrun simctl list(†) returns

9DDA0CFE-7CEC-40B6-A343-1EC01F282B22 (active, disconnected)    Watch: Apple Watch Series 2 - 42mm (88474523-163E-4021-B591-2AECBFA26997) (Shutdown)    Phone: iPhone 7 Plus (5785E680-15CD-42D3-82AB-597286A270C5) (Shutdown)

then run these 2 commands

xcrun simctl erase 88474523-163E-4021-B591-2AECBFA26997xcrun simctl erase 5785E680-15CD-42D3-82AB-597286A270C5

(†) The device ID can be obtained from running

xcrun simctl list

This will reset the simulator (equivalent to iOS Simulator > Reset Contents and Settings... menu item).

With Xcode 6.0.1 (Build 6A317), there is either a bug or a change in behavior where when you uninstall an application, user defaults are not removed.

Usage: simctl [--noxpc] [--set <set path>] <subcommand> ... | help [subcommand]Command line utility to control the iOS SimulatorFor subcommands that require a <device> argument, you may specify a device UDIDor the special "booted" string which will cause simctl to pick a booted device.If multiple devices are booted when the "booted" device is selected, simctlwill choose one of them.Subcommands:    create        Create a new device.    delete        Delete a device.    erase         Erase a device's contents and settings.    boot          Boot a device.    shutdown      Shutdown a device.    rename        Rename a device.    getenv        Print an environment variable from a running device.    openurl       Open a URL in a device.    addphoto      Add a photo to the photo library of a device.    install       Install an app on a device.    uninstall     Uninstall an app from a device.    launch        Launch an application by identifier on a device.    spawn         Spawn a process on a device.    list          List available devices, device types, or runtimes.    notify_post   Post a darwin notification on a device.    icloud_sync   Trigger iCloud sync on a device.    help          Prints the usage for a given subcommand.

Reset all Content & Settings in a single command

1. Quit iPhone Simulator

2. In Terminal, run:

   xcrun simctl erase all

This will reset content and settings of all the simulators for the active version of Xcode (the one referenced by xcode-select -p).