I need a pin for the clasp. It is the spring loaded pin that connects the link to the squeeze mechanism.

I don't know for the swatch specifically but all watches are roughly the same beast. If you look at the side you will notice small pins on the band. With a very small jewelers screw driver and some light tapping you can pop the pins out. The end connections near the watch and then on the clasp side are usually spring loaded which can be removed with a tiny flat blade as well. Just tap out the pins and keep track of them, you will need to tap them back in once you have removed the extra link to make this smaller.

Follow these steps and it will help u resize your watch.
1-Take a good look at the watch bracelet. Seiko watch bands are equipped with one of two different types of pins holding the links in place. One type is a simple, nail-shaped pushpin that's inserted into the joint between two links. The second is a flat, L-shaped piece of metal that slides into the center of a link and locks it into place. Both pins are removed using the same process. If the nail-shaped pushpin is present, you'll see the tiny screw heads in the joints. If the L-shaped pin is present, the links will be open-sided and you'll be able to see a strip of metal inserted in each links.
2-
Look for the arrows on the inside of the watch bracelet links. The arrows indicate the direction the pins and links need to be slid off of the band. Any attempt to go against the arrows could break or warp the links.
3-Remove the spring bar from the clasp with the small pin-removal tool. Set the watch up on it's side so that the top of the spring bar is facing up and the bottom is flush against the table. Put moderate pressure on the top of the spring bar and tilt the watch just a bit sideways so that the spring bar can slide out. Ease out the bar slowly and carefully; the spring bar is spring-loaded and will shoot away from the watch if you're not careful (make sure that the bottom of the watch is pointed away from you at all times). Put the spring bar in a small dish so it doesn't get lost.
4-Line up a small pin-removal tool with the top of the pin and push in the direction of the arrow until it slides out completely. Slide off the link. Place the pin and the link in the small dish. You'll want to save them in case the watch needs to be re-sized again at a later date. Continue removing links, alternating sides of the band to keep it even, until the watch reaches the desired size.
5-Reconnect the watch. On the side opposite where the spring bar was removed, line up the link connected to the clasp and the second link on the band. Slide the pin in the opposite direction of the arrow, using a flat-headed pin inserter to push it into the joint. Use the pin-removal tool to give it a final push, listening for the click.
6-
Reinsert the spring bar slowly, using the pin inserter. Make sure the spring bar is lined up and tightly in place to avoid injury.
Try this and it you cant manage it then you need to get it to a watch repair shop specializing in that brand.

Some clasps have holes in them to allow you to adjust the straps in smaller steps than removing links.

It sounds as though yours in one of these.

The pins are spring loaded just like the ones used to fasten the strap to the lugs of the watch, so you can apply a probe to one end of the pin with one hand, while applying a gentle force in the direction you wish the strap to go with the other hand.

Then do the same with the other side and repeat as needed.

This is usually a 14-16 mm clasp spring bar. Your local watch repair shop should be able to supply it to you without a problem.

This band is put together with cotter pins. To remove the cotter pins look at the edge of the band. The end of the pin that comes out is split and looks like a screw. The end that is solid is the end you want to push from. Use a small punch to push the pin out. The split end is the bigger end of the cotter pin so it needs to come out and go back in the same way it came out. Make sure you remove an even number of links on each side so the watch sits on the wrist the right way. You also have a micro adjustment on the clasp. To adjust the clasp simply use a punch to press the spring bar in the clasp in until it moves. This is a spring bar so be careful it doesnt jump out if the clasp comes apart.

This band is put together with cotter pins. To remove the cotter pins look at the edge of the band. The end of the pin that comes out is split and looks like a screw. The end that is solid is the end you want to push from. Use a small punch to push the pin out. The split end is the bigger end of the cotter pin so it needs to come out and go back in the same way it came out. Make sure you remove an even number of links on each side so the watch sits on the wrist the right way. You also have a micro adjustment on the clasp. To adjust the clasp simply use a punch to press the spring bar in the clasp in until it moves. This is a spring bar so be careful it doesnt jump out if the clasp comes apart.

By finding a spring loaded rod in the clasp (that is in the set of three holes in the clasp) moving it to the last position. However it was still loose, so by finding the spring loaded rods that hold the links of the band together, pushing them down in the direction of the arrows and removing enough links to fit.

Most clasps have a series of small holes drilled in them, and the end of the strap is held in by a small, spring-loaded bar whose ends are seated in one set of holes. Take the end of a small paperclip, or a large needle, and use it to depress the spring-loaded pin. You can then carefully slide it to another set of holes to make the band smaller. Don't let the ends of the pin slide all the way out of the clasp, or it might shoot off into space.