If you wish to discontinue using Microsoft SwiftKey, and remove all data from your Microsoft SwiftKey Account, then you will need to remove your Microsoft SwiftKey Account first before uninstalling Microsoft SwiftKey from your device.
You can do so by following the steps below:
- Open Microsoft SwiftKey
- Tap 'Account'
- Tap ‘Delete Microsoft SwiftKey Account’
- Confirm that you wish to delete your account by tapping 'Delete'
Please note: this will unregister all of your connected devices, and also delete your backed-up data.