Loop through and delete an item from a combo box

I set up a combo box in VB.NET CF using the following code:

sql = "Select ColGUID, Collector From Collectors"  (this is WAY over simplified, but the number of columns and the type of data is the same)

Dim ds As New DataSet
Dim da As New SqlCeDataAdapter(sql, MainForm.conn)
da.Fill(ds, "Collectors")

If ds.Tables(0).Rows.Count < 1 Then
     MsgBox("All of the dust collectors in this location have been recorded today", MsgBoxStyle.OkCancel)
     da.Dispose()
     ds.Dispose()
     MainForm.G.ExitApp(True)
End If

With cboCollector
     .DataSource = ds.Tables("Collectors")
     .DisplayMember = "Collector"
     .ValueMember = "ColGUID"
End With
da.Dispose()
ds.Dispose()
cboCollector.Enabled = True

Now I would like to go back and iterate through each "line" in the combobox and delete items based on a specific criteria ... for example, I would like to do something like this:

With each item in cboCollector
   If condition true then DeleteItem
End With

I've looked at different examples and none of them seem to work ... is this even possible with compact framework? I've tried to exclude the itmes by being creative with my sql statement, but the sql command is just too darn complicated and I can't make it work. The item(s) I want to delete are really simple to find after the combobox is populated.