Using a flat blade screwdriver remove the three special screws in the straight guides at the front of the lens.

Using a PH0 Screwdriver remove the 6 screws and spacers holding the two groups of lenses in place.

Do not loosen the screws with blue varnish inside white spacers. I'm guessing these are to align the lens elements.

The outer barrel can now be removed.

Remember to mark how things are aligned.