It is required that a user create a password for their user account so that it can be accessed in the future.
Do you want the user to have a chance to enter their password if they want to? If you want to remove the ability completely you would need to take out the validation for this field on your confirm pages, both the spry and server side for it.
Depending on what WebAssist tools you have you could also create a new random password for the user and set that during the checkout. Post back and let me know which way you would like to go and I can give you some more pointers on that.