Revert "Added endSession(); to ConsoleUI, SalesSystemUI"

This reverts commit 9136f501db83b2eeb944b895e37a140d6d2a23c1.
Revert "Revert "Added endSession(); to ConsoleUI, SalesSystemUI""

This reverts commit c9bbe05314b2e027953b4f6b78d4f535f2d8c42c.