OF is the best answer to decide a job is not right for you, it is not necesssary to tell the employer.
Step-by-step explanation:
The common reasons for leaving a job is for additional compensation, looking for new challenge, a change in career path, relocation.
We have to give clear reason and explanation for quiting from the company. The conversation should be short and give positive answer.
The reason for exit should be clear like, change in career decided to gain new skill, high salary.