When I’ve potted up figs or fruit trees I’ve just trimmed off the outer layer of soil and roots on the sides and bottom. I’ve done this with hand pruners, a shovel, an axe, or a saw; whatever works best. Just start whacking away, no washing or anything else. It’s always worked for me. And I won’t worry about a few leaves. Esp with my method there are roots in soil left on the tree.
The idea is to clean off the circling roots on the outside of the rootball.