The traditional way is to pull apart, and discard, one of the permanent links. That way you can always add more links, or disconnect it from the clasp.
Yes, the attaching link rivet can be ground off, that link removed, and the clasp directly riveted to the first link. You will also need a sleeve as the rivet is smaller in diameter than the screw-bars. You then cannot change or adjust any links on that side unless you grind off the rivet and revert back to the original configuration.
Here is an explanation of the second method.
https://www.rolliworks.com/post/oyst...link-explained