Importance of Serving Notice Period in Employment
Any formal employment has its own set of rules right from the stage of application for the job to its termination. When a notice period for resignation is prescribed, you cannot simply send your resignation by any means and walk out of the job to join another one. Unless you are formally relieved by your previous employer after accepting your resignation, you are deemed to be in service but absconding. As such, your joining another job would be treated as dual employment by both employers, and eventually, you will lose both jobs.
It is better to approach your previous employer, apologize unconditionally, remit the notice salary if insisted, and obtain the proper documents of your exit.