I was having 2 version of Appium.
One was installed on Windows/Program Files and Other version was .zip extract.
I was not able to start the Appium server and got below error -
error: Couldn't start Appium REST http interface listener. Requested port is already in use. Please make sure there's no other instance of Appium running already.
Start the Windows Task Manager by pressing Ctrl+alt+Del.
Under Processes tab kill the '
Try to start the Appium server again