Correct, you have to uninstall iRite and then install HTMLEditor. As far as Editor you already have in your site, you should not have to do anything unless you are planning to change a setting in the Editor. iRite stores its files in an iRite folder so all the Editors should still work as expected. If you decided to make a change to an Editor, you will then have to Upload the HTMLEditor folder which is created using the HTMLEditor.