What ICA version are you using? Because navigating to the Variable Create/Edit/Delete area depends on the version.
For ICA 11.1.1, at the top-left gray navigation bar, click Report and from the drop-down menu select Variables. That's the Variables playground for adding, editing, etc.
For ICA 11.0.13, use the left-side gray navigation bar, expand the Queries pane, and click the Condition Explorer tab to enter the Variable work area.
Hope this helps,