Find In List / Remove Item And Ignore Case Of Characters In String

I'm having issues with finding something in list, and removing the item, ignoring the case of characters in string.

The code goes:
Dim listItems As New List(Of String)
Dim pattern As String = "AbC"
Dim array() As String
array = {"ABC", "abc"}
listItems.AddRange(array)

Here I'd like to remove all items from listItems, that are abc, no matter what case single characters of item are, including mixed case items. So in this example, every items should be removed
listItems.Remove(listItems.Find(Function(r) r = pattern))

If I change pattern to match the case of item, then item #2 gets removed:
pattern = "abc"
listItems.Remove(listItems.Find(Function(r) r = pattern))
How can I find item in listItems, ignoring the case characters in pattern?