How to remove dust from inside barrel of a Canon EF-S 18-200mm
You'd have to fully disassemble the lens, which I strongly do not recommend doing (especially the plastic lens bodies).
Have you noticed an effect on your images?
Warning: The internet is filled with one sided views. Stay objective.
Unless you have an issue with it showing in your photographs, don't worry about it. Very doubtful you can clean it yourself without trashing the lens. The only alternative is an expensive Canon repair.
Thanks for the replies so far. I am worried some of the dust will now end up in the camera body. I was hoping all I would need to do is to remove the front element? If they cannot be cleaned via DIY any idea what canon charge for cleaning them?
Disassembling and reassembling a zoom lens is no joke. It would probably cost more than the lens is worth.
There is no reason for the dust to work itself from the interior of a lens into the camera body. And if it does, the sensor is (relatively) easily cleaned.
Relax. Take pictures!