A few years ago I obtained this olive from a nursery where it was very sad looking. After repotting the tree I left to get settled in good substrate and regain strength. However, in the spring of 2019 I was really fed up with the big lumps on the trunk and I had not decided on a way to get rid of it, and make it look OK. So I decided to chop the head of the tree.
At the widest point of the trunk I took a saw to it, and horizontally chopped the tree in two. As a result, the top now has a nice wide spread at its base, and I will try to root it as a cutting. The bottom part I sealed with cut paste and a piece of grafting tape to reduce moisture loss, hoping for sprouts at the top of the cut.
Two months later in June, the tree shows new sprouts and the base is set for a much smaller olive bonsai. As a bonus, the new tree snows smaller leaves than the original plant, indicating on a wild strain rootstock.
Could you root the upper part and how did you do that?
One could, by planting it in pumice, put a clear plastic bag over it and put it in a bright warm spot (without direct sun).