Agree it is a very good idea to keep this, especially as @codinghorror mentioned, it is relevant and important information; however:
If you must get rid of it, in this example (on the image, not on the actual notice) try a simple jQuery or a JS selector since the p element of that “auto bumped” notification has no CSS class nor id (see image). Looks like the closest class is “content” but I am guessing that class (did not check the source) appears more than once; so it might take some “selector finesse” to select it…
Update: The CSS selector idea above is only an example based on the image, not the actual autobump notice. Need to inspect an actual notice