Sure. When you register the competition, the street address is optional. You only really needs to register a target city and state. Even that can be updated if you need to move the competition across a boundary line. This is mostly so that when the comp is listed, folks will have a general idea of where it will be held, so that Zymurgy and the various AHA and BJCP web sites can show a reasonable location. As the date comes closer, you'll post more info to email and a web site, etc, with entry location(s) and the judging location. The BJCP doesn't need nor care about that level of detail.
If you do change it, the location, just let Dave Houseman know (email@example.com).