Try this:
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Sub SeekAndDestroy()
Dim strCheck As String
Dim Flag As Boolean
strCheck = Range("A3").Value
Range("AA1").CurrentRegion.Select
For Each r In Selection.Rows
Flag = False
For Each c In r.Columns
If Flag = True Then c.Formula = ""
If c.Value = strCheck Then Flag = True
Next c
Next r
End Sub