Hi,

It actually depends on the modules you are using, you can do as follows:

* take copy of your server or set up a new odoo instance, remove enterprise addons from the path
* uninstall the web enterprise module and any enterprise modules you have used in the db.

Make sure that you are not loosing any data in between. Community is free but with less features than compared to enterprise. If you are starting a new installation, its easier, here you have to make sure no data is lost.

If you are not talking about this and stopping the odoo partneship, the things you will loose is the dedicated account manager, leads you received from odoo and access to the odoo source code and e learning materials.

Thanks