From Extreme Management Center
1. Select Network
2. Select Device
3. Select Devices Tab
4. Select Device you want to use ExtremeShell and highlight with left click
5. Right Click on device and then select Device
6. Select Open Device Terminal
7. The Shell/Terminal will then attempt to login to the device using the CLI credentials configured for the device.
8. To Exit the shell, you will need to hit X on upper right.