how to clear Zoho crm lookup field

how to clear Zoho crm lookup field

How can I clear the value of a Creator Zoho CRM field with out using an API call?

I want to be able to clear a value that has been entered.

I have used the following but it seems to use an API call and i dont think it actually is clearing the value.

input.ZohoCRM_Lookup_Field = null;