http://msdn.microsoft.com/library/default.asp?url=/library/en-us/cpref/html/frlrfsystemdatadatarowcollectionclassremovetopic.asp
and
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/cpref/html/frlrfsystemdatadatarowclassdeletetopic.asp
are the two links worth reading.
Brief summary to delete a Row call the .Delete method as this marks it for deletion, .Remove is the same as calling .Delete followed by .AcceptChanges and will result in it no longer being seen as a modified row.