I wouldn't. Avocados drop a lot of leaves to create their own mulch at their base. You don't need to hasten the process, just wait for them to drop naturally and resist the temptation to clean it up so it will "look tidy". As long as the new leaves look nice, you've got a healthy plant.
If the black spots are on the oldest leaves, then yes that is normal for avocados, they will also tend to turn yellow before dropping.
The avocado is an evergreen tree and just like a magnolia will keep leaves year round with the older leaves turning and dropping to the ground.
As has been mentioned, these leaves become the tree's mulch and help replenish the soil for the trees growth.
As long as the black spots don't show signs of being Black spot mold, I would not worry about the tree.