Company forcing to serve notice perriod

Hi, According to the contract letter I have signed at my current company, the notice period conditions are as below: "Every employee is expected to serve and work for three months as the notice period except in case of non-confirmation of employment during probation period, redundancy or termination on disciplinary grounds. The notice period does not include the employees' vacation time or their days off. At the Company's sole discretion, the employment may be terminated and a payment in lieu of notice period may be given. When an employee is being terminated, and if the company chooses not to let the employee work during notice period, salary payment will be made up to the last day of notice period. In the event that an employee requests to leave the Company without working their notice period, the Company reserves the right to charge the employee their equivalent base salary and relevant allowances in lieu of this notice period." According to me, the last three lines clearly state that in case I want to leave early, I can pay in lieu and exit. However the HR is telling me that my manager needs to approve my request to be relieved early. Please advise on this matter.