To delete a custom perspective layout that has been saved under a name other than one of the six default perspective names, go to the Window Menu and select Preferences (screenshot). With the preferences window now open, click the arrow to the left of General, to expand its contents, and then select Perspectives. Next, select the desired perspective from the list and then click the Delete button. A new window will open, click the Yes button (screenshot) and then click the OK button in the preferences window to save the changes and exit (screenshot).

Note that a custom perspective layout that has been saved using one of the six default perspective names (i.e. Portfolios, Queries, Reports, Research, Symbols, or Watch Lists) cannot be deleted, but rather, can only be reset back to the the original, default layout.‍