I had to bump my interview a month due to a family emergency (even though United says no deferrals/changes in their communications). I'd recommend continuing forward with your interview date and email the hiring team and communicate what's going on. If they call you for an interview, it means they want you. But life happens and they can be flexible. Just ask. Worst case is they tell you to reapply but if you pull it yourself, you HAVE to re-apply...