Hi, When did you join that company, and how long have you been working for them? What is your role and what are your responsibilities?
Notice Period and Employment Terms
It is true that in the absence of any proper employment terms, a notice period is not compulsory. However, if you leave without notice, the employer might not issue a proper relieving letter or experience certificate as well.
So, if you have been working for a considerable amount of time, I suggest you serve a proper notice period, hand over your responsibilities, and get properly relieved for mutual benefit.