Mild = remove all suckers around the base of the olive tree, cut out any dead wood, cut canopy to 2-3 meters, remove any cross branches inside the canopy. Lie on the ground with your head touching the trunk. Look up through the canopy. You should see light. If you cannot see light, then thin out some more. Spring should bring new shoots and some flowers on one year old wood. 

Severe = remove all suckers. If there is a single trunk, follow this up to the scaffold branches. There should be 3- 4. Get out the saw and saw about 0ne foot along the scaffold branches. A sorry looking olive tree! Paint areas that are likely to get sunburnt with white flat plastic house paint. Spring will bring new wood, but you will have to wait another season to get flowers and fruit.

Happy cutting and sawing - Professor Stan Kailis, University of Western Australia, Perth WA