Yes, you can simply logout Alexa in the WiiM Home app by these steps:
- Go to the Browse tab, then select Amazon Alexa.
- Tap Sign Out to turn off Alexa.
You can always sign up Alexa in the WiiM Home app for Alexa Cast and Alexa voice control. For details, see How to Stream Amazon Music to WiiM Devices Using Alexa Casting and How to Use Alexa with Your WiiM Device.