textbox clear

Combobox - objCombo.items.Clear()
Datepicker - see here[^].

If it is not a databound control call ComboBox1.Items.Clear for Combobox
I am not sure whether Datetimepicker has such a property. May be you can set the selected date instead of clearing it.

Please, I told you once, edit your post, don't post fake answers

'cboPackage.items.clear it works but how to make the items in combo ox fill again.'

You are so cool with your h4ck3r nick and all, but it's clear you know nothing about programming. You should buy a book rather than bringing your most basic questions here. When you empty it, how do you think you fill it again ? You have to run the code that fills it, because whatever you put in there before, you've told it to throw away.