What is ARS or SO?
Anyway, it may happen that due to the non-availability of the role prescribed in the offer, they have given you another role just to accommodate you. In fact, before that, they should have discussed the matter, and that is a serious fault with the management. Now, if you are not okay with the post given, submit your resignation and go. Obviously, you will be on probation now, and you can get relieved even without notice by showing the reasons. But in your case, you have a reason to show, and you can very well ask them to relieve you immediately upon getting another job.
Therefore, find another job that is appropriate for your qualifications and experience.