The idea it to make a little ramp so water flows away from the wooden post on all 4 sides.
Replace rotted fence post in concrete.
Mark cut lines onto post with a layout square.
Set the depth of cut on a circular saw to cut through the posts but not into the rails.
Position the lines above and below each horizontal rail.
If you have an old wood fence post that is completely rotted off and you are able to remove it along with all debris you could reuse the cement ball for a new post.
Look for copper naphthenate solutions at home improvement and paint stores.
You can apply the solution by brushing it onto the post or dipping the post into a tub filled with the liquid.
Project step by step 5 dig the right size hole.
Dig a semicircular hole around one side of the concrete pier.
This way the post will not be sitting in cement to rot off again.
Break up the concrete.
Remove the old post.
How to replace fence post anchors in concrete or fence post spikes without concrete.
Saw along each pencil line.
Make the hole large.
Some have successfully used fence post anchors.
Using a small shovel to slope the concrete away from the post.
Use a sledgehammer to break up the concrete around the old post.