Plasmid gene knockout
Well the simplest way is to cut the gene at the both ends from operon by means of proper restriction enzymes but in case that you get more than one recognition site then you can use microRNA or proper oligo to make a hairpin loop and break that part 
If you only want to silence the operon then you just need to cut it nearly at middle of the gene and ligate it with a nonsense sequence, then it will loose it's functionality.