Usa a thin metal blade of some sort to loosen the metal cover from the tip of your lens. It is attached with an adhesive tape. Move the blade gently around the lens, it should come off quite easily. If you have problems, consider using a hairdryer or heat-bag to heat up the lens cover.

When you have gently moved the blade all around the lens a couple of times, gently tilt the blade, forcing the cover away from the lens.

Note the direction of the lens cover for the reassembly. There is a tiny notch on the bottom of the cover, so it will only fit this way.

Be careful not to bend the lens cover! It is very thin and easily bent.

In my camera, the curtains got stuck after cleaning when putting the cover back on. I solved this by pulling the cover a bit. It turned out too much pressure when reassembling will make it get stuck again.

The adhesive on the inside of the cover is possible to reuse when reassembling. Make sure it does not clump or gets dusty, in which case you would need to replace it with a new adhesive.