I'm a beginner in repairing bicycles. I have quite an old town bike. I'm trying to change the tires. I have trouble in taking out the back wheel. As you can see in the picture, there is a small piece of chain connected into the hub shell.
I've checked for a small clasp or small screws to remove it but it doesn't seem to have any. Does anyone know how to remove this? Or am I doing something wrong? Any help is appreciated.