On the main screen with the big digital clock screen widget, just hold it for a couple of seconds and it will suddenly have a big green border round it and you will also now see a REMOVE button at the bottom of your screen (Same as when you remove any app from any screen). Now just keeping your finger on the widget drag it down to the REMOVE button and it disppears.
Once you have done that, simply hit the + which is bottom right, choose widget, and then choose Clock (HTC) - It will now give you the option to scroll right selecting different clock faces, and the one you want is I think the third one. Just follow the prompts for the location and dont choose current, choose your city - If it's not there just add it with the option at the top of the list.
You can try adding the widget on any other screen first if you want to be comfortable that it works. There are lots of other widgets to play with too. My favourite is the Power Control (Android) which gives you a simple bar with 5 buttons that allow you to toggle on or off your Wireless / Bluetooth / GPS / Synch / Brightness - Brightness one has 3 settings that you achive by simply pressing the button - DIM (Great at night for me) / Medium / Bright - Love it.
Regards
Ken................