The wiki workflow describes the process of change in the wiki. All changes must adhere to the Style Guide.
To rewrite a god that exists completely, it must first be proposed on the forums. If a community manager gives permission and there is no backlash over the overhaul suggestion (include exact changes -- e.g. "Terrae should become a god of pasta with the challenges and lore x, y and z") after a week you may rewrite the article. Be sure to adhere to the template and style guide.
God creation works similarly to an overhaul request; an exact description of the god, with community discussion. Community manager permission is not required, but generally recommended. Follow the God Creation guide.
General changes can be done at any time as long as a proper message is given on what the change was. Grammar, writing and changes like that can be done without discussing it with the community first. Optional challenges should be proposed first however, but do not require as much permission. However, they may be removed at any time -- it is generally best to place these in the forums for that reason.