When a recruiter or a hiring manager set an interview with you, it means they allocated time specifically for you.
You have all the freedom to change your mind for whatever reason but in terms of best practices, I highly recommend calling to cancel as soon as possible.
It is very inconvenient to wait for someone to arrive to a meeting they willingly confirmed but then not to show up. Many times, recruiters call candidates back to ask if they had an accident on the way but they wouldn’t even pick up to explain what happened.
Some recruiters will even put a note such as “Don’t call again” because if you were rude to them you are likely to be rude to their customers as well and not honor your commitments.
Many will say, yes but companies also stop giving feedback after the interview and that it is rude as well. I totally agree, but 2 wrongs do not make a right. The people may come and go in the company but that note will stay on file. What if 3 years later you saw another opportunity and wanted to apply?
For the sake of doing things respectfully, just inform the people who are waiting for you that you won’t be showing up. Keep communication channels open; maybe you were not ready today, you were going through a difficult situation, you woke up sick, you did not remember that you had an exam, received another offer or simply decided that you were not interested in the vacancy anymore. It does not matter.
Some recruiters will ask themselves if the candidate is not interested, why did they bother to apply at all? What you need to know is that if an employer called for an interview, it means they saw something they liked in your profile and how you conduct yourself is your control.
It goes without saying that if something came up and you’re still interested in the vacancy, contact the recruiter to reschedule as soon as possible to avoid passing by an opportunity you were looking for.