Thank you for posting your query.
Firstly, Congratulations on Making a Big Decision in Your Professional Life
Not many people in Dubai, UAE, are in a position to make such decisions due to the following reasons:
• Comfort with their current financial situation.
• Waiting for the bonus.
• Not skilled enough to take on a challenge elsewhere.
• Having too many loans or liabilities and thus cannot leave their current position.
• Visa and NOC issues.
Considering the fact that you have overcome all such nuances, you need to reflect on why you were served the warning letter in the first instance.
1. If it is a disciplinary issue that was highlighted, then you should be apologetic and ensure your behavior does not offend or stray away from the policies and procedures of the organization.
2. If your manager does not like you and has a habit of issuing warning letters, then smile and accept it. You have decided to be part of the organization. If you don't like the way they operate or their corporate guidelines do not match your philosophy, then resign. No one has forced your decision. What's the point in complaining?
Answer to Your Question
Yes, the organization has every right legally to issue a warning letter.
How?
Well, you need to look at the timeframe and the change in your behavior since you tendered your resignation.
1. Have you been praised by colleagues for making the right decision? If your decision is right, why have they not resigned with you?
2. Have you resigned on a poor note or due to a conflict of interest with your organization? If you don't like them, move on. If you feel you are always right, then you should aim to be a Board member.
3. Have you resigned and become more vocal and critical in your daily comments regarding the working conditions and the management? You have resigned because it is your decision. Who has given you the right to defame or speak negatively?
You need to understand that on legal grounds, you may be impacting or influencing other employees' behavior and productivity. If you are making poor comments and statements, then you are surely looking for a mandatory ban enforced on you legally if proven guilty.
You have resigned, so move on. Is it a career you want to build, or do you want to look like a superhero in front of a few colleagues who will never be part of your life in the future?
Regards,