Hi @jkl2337, welcome to the Sonos Community.
You shouldn’t have to unpair the devices to get Alexa playing by itself. I don’t use Alexa myself, but when issuing a voice command, it’s generally better to specific the name of the room/speaker you want to use.
So if you want to play just on the Alexa speaker, you’ll say the same command but add what you’ve called the device in the Alexa app to the end. For example, if the Alexa device is named Bedroom, you’d say ‘Alexa, play Music in the Bedroom’.
If this doesn’t help, it’s probably better to reach out to Amazon for further help and they’ll know more about their own device and why it’s not letting you play it by itself.
I hope this information helps!