This is my Seiko SRP311 bracelet adjustment. The most important thing to note is the small collar that locks the pin in place. Lose that and its difficult to get a replacement.
The Seiko SRP311.
First disconnect the bracelet from the clasp.
Don't lose the spring bar.
Its actually easy to push out the pin from the locking collar. The locking collar is that small thing that you see in the picture below. Don't lose the collar.
The bracelet disconnected. You will need to remove another link to shorten the bracelet.
Another link removed. The rebuild is the opposite. The main thing to remember or note is that you will need to push the collar a tad into the link to fully lock the pin in the link. Use the other pin, the head side (the larger side) to push the locking collar fully into the link to lock the pin. You don't need a hammer for this, but it helps.