WARNING: This page is about a different car, the 2007 Mazda MX-5 Miata. However, it is still accessible from the selected car via links, so may be relevant.
Lock the disc plate by applying the brakes.
Knock the crimped portion of the locknut outward using a chisel and a hammer.
Remove the locknut.
Fig 1: Knocking Out Crimped Portion Of Locknut Outward Using Chisel & Hammer