Removing ‘hangovers’ from failed XP installtion on external disk

I began to install XP on an HD connected to my laptop via the USB connector.

The installation failed & I foundanother way of installing XP on that disk. However, now I am left with ‘dual boot’ when I start my laptop.

Boot 1. Win XP Pro – the failed installtion
Boot 2. Win XP Home – My original ‘live’ XP

How can I remove the dual boot & leave it asit used to be with just XP Home.

Thanks