master password in 10.3.9

I set a master password on my imac using OS 10.3.9. I no longer need
that feature and would like to undo this action. I can change the
password, but so far am not able of disabling it altogether, even when I
leave blanks for the new password and confirm new password options. It
insists I create a new password or continue with the old one.

Any way to be rid of this? Thanks for any info.

bill