How to delete(hide) value in combobox

Hi everyone,
how to delete(hide) value from this box.
This is my form.



I want when close the form to make the field empty like this.


Where to write a code or override a method and what to write ?

What do you mean by deleting the value from the box? Can you explain the requirement in detail?
Is that a bound/unbound field? What is the purpose of this form?

I get values in filed JOURNALNAME from table PRICEDISCADMNAME. This box make list of values from field in colum and choose one of them and this is all.I want when the value is selected and the form closed the value not to be selected or to be empty

Still not clear? Does your form has any data source and the Name control is assigned to any field?
If it is not assigned to any field or it is an unbound control the value in that form will be empty when you open it again, unless you are saving the last selected values.