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