That should not be a problem, however some backup solutions, like older ArcServer, tend to have a username and password as admin, make sure you change those too.
Besides, just change it, test everything, if something fails, correct it or put the admin pwd back.
Marc
If 'something' 'somewhere' gives 'some' error, expect random guesses or no replies at all. Please specify details.
Free Tip: The F1 Key does NOT destroy your PC!