According to general employment practices, it is recommended to provide a notice period when resigning from a job. A notice period allows your employer to find a replacement for your position and ensures a smooth transition for both parties. In many cases, a 30-day notice period is considered standard and professional. However, since you mentioned that you have only been working for a week and have not received an offer letter, it is understandable that you may not have a clear understanding of the company's policies and procedures. In such situations, it is advisable to communicate your intention to resign as soon as possible, even if it is within 24 hours. It is important to have a discussion with your boss or the HR department to explain your reasons and discuss the best course of action. While it is not ideal to resign without a notice period, it may be the only option in your case. It is important to remember that every company has different policies and procedures. Without an offer letter or formal employment contract, it may be difficult to determine whether your employer can take any legal action against you. However, it is always recommended to handle the situation professionally and have open communication with your employer to avoid any potential issues or misunderstandings. It is advised to consult with an HR expert or seek legal advice specific to your situation for the most accurate information and guidance.