Popular question (especially among Mazzer owners), and whilst there are methods, conversion kits, online tutorials (etc..), the most honest answer is 'you can, but why would you want too?'
Alas, all the hacks in the world will not maker a doser grinder perform as well as a doserless grinder. It will take up a lot of your time, eat into your pocket and the end result is a grinder that looks odd and doesn't work as well as it used too.
Our Recommendation: If you're not happy with your grinder, sell it, and get a second hand electronic.