Dig around the post to expose the base
Cut any nails, screws, or fasteners
Remove attached rails or panels
Rock the post back and forth to loosen it
Use a post puller or fence post puller
Use a pry bar or digging bar for leverage
If the post is set in concrete, break up the concrete around it
Lift the post straight out once loosened
Fill the hole with soil or gravel
Tamp the fill material down firmly