(Applies to: all versions of FusionBB)
If you are allowed to edit posts, you can click Edit
next to the post you wish to remove. At the top of the screen you will see a radio button giving you the option to delete that post.
Note that the administrator may put a restriction on your ability to edit, or the timelimit you are allowed to edit/delete. If you are not allowed to edit or the time limit has passed, then a moderator or administrator will need to delete your post for you.