Use Command -> Manage arrays to open the External data dialog.
It contains the list of labels, representing all arrays already loaded.
For each array you can view its numerical data. Mind that the dialog displays no more than 100 points. If an array contains more points, you should specify the range of points to display either in terms of points ordinal numbers or in terms of abscissa values.
Check in View all checkbox to observe all columns of the file, not just the columns used for coordinates.
Click Show to display data .
Using this dialog you can switch on / off markers for each arrays. Markers are displayed to mark array points when corresponding graph is plotted.
To delete array select it and press Del or select Delete from context menu .