Trending @HCL; IMMEDIATE release from 90 DAYS NP

Hi everyone my new company has requested me to join ahead of time and it's been a week since i resigned, i requested for early release but he asked for L4 APPROVAL, SO i decided next week to go and submit a laptop to the office and end this , will there be issue I request to legally with basic pay but they are asking for medical documents as I gave medical reason.Any way out