I'm not sure you can actually make yourself fully incontinent without having some type of surgery done.
But you can help to weaken your bladder muscles by not holding in your urine and just peeing before your bladder gets full.
If you start just peeing before your bladder is full and stop holding your urine in you'll eventually start wetting your pants or diaper without realizing it.
I know after I've worn diapers for awhile I've started to just urinate whenever in my diapers without realizing it.
I'm not sure if I'm incontinent now or if it's just because I've trained myself to wet my diaper without knowing.