you deleted or commented out a "core" required field. so the validation is freaking out -so to speak
if you want to change the fields, required or not you need to change them in the core. not recommended at all because they are there for a reason, plugins or other user reasons.
im not sure of the pathways to all the files that need to be changed but you start here: oc-includes/[size=78%]osclass/frm[/size]