Summary

Can't clear date picker field on customer portal even if the field is not mandatory.

Steps to Reproduce

1. Create a service desk project
2. Create a date picker custom field
3. Make the custom field visible (not required) in an request type on the customer portal
4. Try to raise a request with the request type from the customer portal
5. Set any date on the date picker field
    

   Expected Results

   We should be able to clear the value in the date picker field if it is not mandatory.

Actual Results

We can't clear the value in the date picker field without reloading the page.

Workaround

Reloading the page is the only workaround but other fields are also cleared together.
We should be able to clear only the date picker field.