The Historical Data Viewer page allows you to delete an existing pen group. To do so, follow the instructions below.
1. Expand the pen group drop-down list in the Historical Data Viewer page's tool bar (i.e. the drop-down list to the far left in the tool bar).
2. Select the name of the pen group you wish to delete.
3. Click the Tag Selector button. The Tag Selector dialog will open, and the text Currently Editing <Pen Group Name> will appear in its title bar (where <Pen Group Name> is the name you configured for the selected pen group).
4. Click the Delete Group button. The Delete Group? dialog will open and request confirmation that you wish to delete the referenced pen group.

5. Click the Yes button. The tags belonging to the selected pen group will be removed from the Selected Tags/Queries for Plotting list in the Tag Selector dialog.
6. Click the Close button. The Tag Selector dialog will close, and the tags belonging to the deleted pen group will removed from the graph on the Historical Data Viewer page.