My 360 degree photo comes from Ricoh Theta S. You can use any panoramic instead.
GIMP is free and open source. Get it here
Open your image in GIMP and go to Polar coordinates filter as shown below.
You can use offset angle to rotate the image. I kept map from above unchecked. You can experiment with that parameter.
Time to crop the image.
Export the image as shown.
Ok, Here is the result.