remove year from birth date

May we know which Form are you referring to?

You can add the Birth Date picker widget in your Form:

Next, hide the year dropdown from it by injecting custom CSS to it.

#input_5_year {
 display: none;
}
#sublabel_year {
 display: none;
}

To inject custom CSS please follow this guide:

https://www.jotform.com/help/117-How-to-Inject-Custom-CSS-Codes

Guide to add a widget:
https://www.jotform.com/help/252-How-to-Add-a-Widget-to-Your-Form

Hope this helps!

Thanks.