From Trader Workstation, go to the Trade menu and select Option Exercise. 

The Option Exercise window will appear and the Current Long Option Positions box will populate with those options held long in the account.  To exercise one of them, left-click on the option desired so that it is highlighted.  In the bottom left corner of the Option Exercise window, click the Exercise button. 

A window will appear allowing traders to adjust the number of contracts to be exercised.  This window will also warn traders that are submitting an exercise request for positions that are out of the money.  To exercise out of the money options, traders must check the box that says Allow exercising out of money options.

Once this is done the option will move into the Outstanding Exercises box until the clearinghouse processes the request.  Once the option is moved to the Outstanding Excercises box, the action/request is irreversible.