The 660 is LAMS approved as is and doesn't require any additional restrictor plates (etc) to be fitted. So nothing to remove
Here's a comment from Yamaha's own website ...
Learner Approved Motorcycles (LAMs) can be ridden by learners in most states (but not in WA currently). These are motorcycles up to 660cc capacity and a power to weight ratio not exceeding 150 kilowatts per tonne.
Hope this helps.