Why cannot I remove the "Closing Date" from Potentials please?

Why cannot I remove the "Closing Date" from Potentials please?

Hi
In my industry we can take 1 month or 2 years to convert a Potential into a PO.

So I have to keep entering a meaningless Closing Date every time I convert a Lead to a Potential on Zoho.

Is there a way of getting rid of it please?

Thanks

Nick