Remove your grinding/cutting tool by simply pulling it off the spindle.

Next remove the disc flange (a.k.a spacer) by pulling it off of the back end of the spindle.

The disc flange has two small raised edges on its back side. These ridges need to be aligned with the two flat faces at the back of the spindle lock when reassembled. This will ensure a safe, snug fit for your grinding blades.