Delete Birth Year?

[Wingz]

I'd like to delete the birth year - I've found it causes a lot of balks at registration resulting in abandoned carts because of the perception of privacy issues/identity theft - however keeping the month and day for use in the birthday present module.

 

is that possible (using the override system to keep it from erasure during upgrades)? And if so, could someone please share the process?

 

Thanks in advance.