emulator-5554 refers to your Bluestack application in windows
you need to stop or kill those services, to do it follow the steps
1. Open Run command: press start and type run ( or ) press Window key +R
2. type "services.msc" and enter
3. wait for some time and this should open a window
4. In the new window, select "BlueStacks Android Service" and click stop [you just need to stop that service]
5. Now check in adb with "adb devices"
6. This should have removed the additional emulator, so you can continue with the rest of the process
If above steps didn't helped then try "adb -e reboot"