Once you decline, it's highly likely you won't be offered this position again. Turning down a job might feel intimidating, but when it's done well, it will enable you to keep your professional network intact.
For example, your email could say something like, thank you for offering me this position-- it's a great opportunity. However, after careful consideration, I have decided to accept a role with another company. Or I have decided not to move forward with this position. Thank you for your time.
You don't burn bridges if you respectfully decline any offer of employment. Just say, ``Thanks for the wonderful opportunity; I really wish I could work with you but I just accepted something else.'' You don't owe them an explanation of why.
How to Reject Candidates Without Burning Bridges Reject Promptly (and Kindly) ... Personalize Emails When Applicable. Request Feedback on the Candidate Experience. Consider a Phone Call For Late-Stage Candidates. Notify Promising Candidates About Future Job Openings.
Resign in person: Schedule a meeting with your boss or use an existing meeting. IF you can't do face to face, do Zoom or phone call. Let them know that you are resigning thank them for the time you had there. At the end of the meeting hand over the letter or hit send. Send a copy to HR as well.
Focus on the matters that influenced your decision without mentioning why you accepted a different offer. When you turn down a job offer while being positive about it, you won't burn bridges. You reassure the employer that your decision wasn't due to their shortcomings.
Tell them you appreciate their offer and are glad they picked you for the job. After that, mention that you will not take it and give them a reason. You don't have to go into much detail, but it's good for the employer to have a clue of why you declined their offer.
Here are Four Effective Ways I Use to Say No: Share Your Priorities. Tell the Truth -- All of It. Deflect -- No, But Here is Someone Who Can. Reduce - No, But Here is What I Can Do.
First to answer your question: No, turning them down will not burn any bridges or affect your future employment with them.