Hi Chuan,
yes, that is exactly a Seagull ST2530 movement, and the pin that you outlined is the pin that you should push to release the stem.
All you have to do is setting the crown in winding position (full push in), gently pushing the pin with a needle, pulling the crown out, and the stem will come out easily.
Just, please note that, after removing the movement out from the case, to get access to the datewheel you will also need to remove the dial, the plate under the dial, and the power reserve module that is there too.
All in all it is a tricky task, I would not recommend you do it without help from a friend watchsmith.