Once the bolt has been undone you can move the plate to the side and this will immediately de-restrict the throttle. The locking bolt can be kept in place with a new lock nut. Of course, this will affect the fuelling set up of your Monster and you will need to talk to your Ducati mechanic about the best way to handle this.
NOTE that modifying the motorbike in this manner will negate your factory warranty (if your bike is less that 2 years old) and your bike will no longer be LAMS approved. It should only be done after you have passed your restricted examination and you are riding on a full licence. However, it is a simple process to reverse by putting the plate back in the original position.