How to make Essentials overwrite /spawn command?

By default, when there is a command conflict between plugins, Essentials prioritizes the other plugin over itself. However, you can override this behavior by using the 'overridden-commands' section in the Essentials config.yml file. Adding commands to this section tells Essentials to retain control of those commands.

If you want Essentials to take precedence over our plugin, you can create an alias. For example, you can alias 'spawn' to 'espawn'. For more information and examples on creating aliases, refer to the Bukkit wiki page on commands.yml and aliases.

See http://wiki.bukkit.org/Commands.yml#aliases for more information.