Select the line or bar chart.
Click the Layout tab under Chart Tools.
Click Trendline to remove or add trendlines:
Linear, Exponential, Linear Forecast, and Two Period Moving Average.
Click Lines to hide Drop Lines, High-Low Lines or Series Lines.
Click Up/Down Bars to hide or show Up/Down Bars.
Click Error Bars to hide/show error bars with using Standard Error, Percentage, or Standard Deviation.