If you are using the CSS Form Builder you can safely remove all of the validations that are occurring on the form and create your own with Form Builder.
To expand on what I mentioned about removing the spry validations is that the spry validations have their own labeling that does not correspond to the form elements name.
For example on the user registration full page the first form element is the email address. If you click on this field you will see a bluish colored tab around the element. In the tab you will see information about the spry validation including the validation name for that form element. For the email field it is sprytextfield1.
So to get rid of the corresponding spry code for this element you would look at the spry script code that starts near line 866. In this list of spry validations you would find the one that matches the element and remove it. So if you wanted to remove the spry validation for the email field you will need find the entry for sprytextfield1 in the list of scripts and remove that one.