On my last bike the lock was removed and something homemade fabed up... Nothing complicated, but it got the job done. In general you may not want to make it very conspicuaus that there is no lock. I little bit of staring and a little
and you should have an idea of what you want to accomplish, and a little time at the hardware store should get you there. What you do will all depend on how clean you want the work to look and how easy you would like it to get the seat off of the bike.