A study template selection is the study you have selected from the "My Studies" menu at the bottom of the charting window. The example below shows a Stochastic study using an 11-day window size and 3-day moving average as input parameters. This is indicated by the chart itself as well as by the entry at the center bottom of the screen.
The "Clear Study Template Selection" feature on the Chart menu (shown below) removes the study from the chart, but not from the menu. It will remain on the menu so that it can be selected for future analysis.
An alternate method of clearing a template study is to click drop down the "My Studies" menu (click the arrow at the right side of the study box) and then choose "No Studies."