Cocking indicator - Hit it!
Don't force it, get a bigger hammer!
The pin is held in place only by the detent screw on the left hand side of the receiver. Line the notch in the screw up fair with the pin and drive the pin out.
Problem is that the tumbler has a square hole and is a tight fit on a square on the shaft. Usualy a bit of encouragement will get things moving. If you can drive it through just 1/8 inch, it will pop right out.
Use a brass drift square to the end of the pin, then tap, tap, TAAAAP, pop! If the far side of the receiver is supported, you won't hurt anything. Those are tough rifles built for service in the field.
Once out, dress the square on the shaft a bit with a stone or fine file, make sure that there are no burrs. The tumbler should be a nice slide fit on the square with very little play.