Remove the speedometer:
The first step is to remove the motorcycle digital speedometer from the vehicle. It's a bit of a pain, but it's not terribly difficult to do as it is almost the same procedure as would be followed for replacing the headlight.
Inside the housing that covers the headlight you'll find two connectors that snap into the speedometer, held in place with release tabs, as well as two nuts that hold the bracket in place: Note how these go together before taking them off - make a drawing and/or take a picture before you take everything off if you aren't sure.
Open the speedometer:
Place the speedometer face down on a clean, un-cluttered work area on a surface that you don't mind scratching: It's recommended that you put a rag or old towel between the face of the speedometer and the work surface.
Now, notice the soft, aluminum ring around its perimeter: This holds the clear, plastic cover to the body of the speedometer by virtue of crimping between those two pieces a rubber gasket.
Wearing leather gloves to prevent being stabbed during this step, use a medium-sized blade screwdriver - preferably one that is somewhat worn out with rounded edges - and slide it between the aluminum ring and the plastic body of the speedometer on the back side, prying the ring open as you go along, straightening it out. With a bit of practice you can firmly slide the screwdriver along the perimeter and straighten out that soft, aluminum ring and you will probably have to go around several times to do the job.
The soft, black, aluminum ring around the perimeter of the speedometer that holds the faceplate to the body. Carefully pry this straight.
(This picture was taken after I'd already opened and repaired it - and partially closed it again.)
Click on the image for a larger version.
Once you get 75-90% of the backside of the ring straightened out, you'll be able to pop the ring off the front: Set it aside. With the ring removed you should be able to use your fingernails and pry the front, clear cover from the body of the speedometer.
Be careful with the black plastic rod under the push button, noting carefully how it is installed and taking care that it doesn't fly off somewhere!
Once you have the cover off, set it aside with the black, plastic rod laying inside the cover.
Remove the needle:
This is sort of tricky and it is possible to ruin the speedometer with this step: Since you have already declared the speedometer to be a total loss, you shouldn't feel too bad if you do.
First, note how far the needle is pushed on to the spindle: You'll want to remember this when putting it back on.
If you have very strong fingernails, try pulling the needle straight off the speedometer, but whatever you do, apply tensions EVENLY - that is, pull straight out on the needle as you do not want to bend the spindle! When you pull on the needle make sure that the speedometer is on the workbench with padding on it because if it comes off suddenly, you don't want to slam your hand or the speedometer into the workbench and break something!
If you can't remove the needle with our fingers, you'll need to apply a bit more force. Cut some pieces of paper or thin cardboard (such as from a cereal box) so that you cover the entire face of the speedometer, but allow access to the needle and its spindle - this being done to prevent you from accidentally marking up the speedometer face.
Now, using two medium-size blade screwdrivers, pry the needle evenly off the spindle using the paper/cardboard to prevent damaging the speedometer face: You may want to wrap a rag around the body of the speedometer and clamp it gently - but firmly - in a vise. Hopefully, the needle will come up without breaking anything else! If you do break something else, save up for a new speedo!
Remove the speedometer module from the body:
Using a small screwdriver blade or, preferably, a similarly-sized and shaped piece of plastic, carefully pry up on the face of the speedometer. The face is actually printed on a piece of fairly heavy, self-adhesive plastic that is about as thick as a postcard - and it is this, not the actual body of the speedometer itself - that you want to pry up. It can be a bit tricky to get purchase on the speedometer face and you might bend into a hook a small piece of metal such as a paper clip to act as a tool.