For Windows:
Please update your Edge Cloud using the following link:
https://docs.thetatoken.org/docs/theta-edgecloud-client-installation-instructions#22-windows-version-alpha-preview
Once updated, you should see a "BACKUP WALLET" button. Click it to save your keystore to your computer. You can then access your wallet at:
https://wallet.thetatoken.org/
For Linux:
By default, your keystore should be located at:$HOME/.edgecloud/key