Hi, please don't take anything personally on the work front. Work takes up a significant percentage of your life, and when you execute work with zeal, you will not feel depressed. Lack of interest in doing the work leads to feelings of disappointment, bitterness, and lack of interest, resulting in job dissatisfaction.
Anyway, now that you have already submitted your resignation and are serving the notice period, wherever possible, try to complete the notice period as per the terms and conditions of your employment. This will help you receive a proper relieving experience certificate.
However, if you are very keen on getting relieved immediately, please check your employment terms. If your employer agrees to payment in lieu of the notice period, then for the remaining notice period, you can make a proportionate amount of gross salary. This way, you can get relief along with a relieving letter. But please do not disclose to your current employer that you are holding a better offer.
Please do not opt for termination as it will leave a black mark on your career. Also, if you abscond and join a new employer, your current employer will take some time to initiate disciplinary action and close your file. Meanwhile, if you join with your employer, that would result in dual employment and a mismatch in PF. So, please don't be hasty.