How do I turn down an interview because I have already landed a great offer?

Example answer:

Dear [their first name],

I hope you are having a wonderful day.

I wanted to let you know that I have received and accepted an offer from a different organisation. It is an exceptional opportunity that was difficult to turn down. As a result, I won’t be able to attend the interview on [date] at [time].

I also wanted to say thank you. I have thoroughly enjoyed the hiring process so far and getting to know you [include other people from the team if relevant]. It truly does seem like you’ve built an awesome team.

I would love to stay in touch and hope that we cross paths again in the near future.

Thank you again and keep well.

[your name]