You should be able to cut the chart, and Paste Special, paste as an enhanced metafile. It won't be an editable chart anymore, but it will be native PPT shapes instead of a picture (you will need to ungroup the chart after pasting to convert it to shapes)

You won't be able to edit it as a chart by entering the data tables, but it will be vector shapes which would be much better than a bitmap picture. And, you will be able to edit/delete individual shapes if necessary.