How to draw a trendline but not show the original line?

[Sunny Rio]

I have a basic line graph, I can add a trendline to each set of data, but if I try to delete the original jagged line, the trendline goes too. I only want to see the trendlines.

I can make the original line invisible, but this is a very clumsy way to do it and leaves lots of stray labels at the bottom.