My employer is not accepting pay in lieu

I have a 2 month notice period which i wanted to reduce to 1 month using the pay in lieu clause, since 1) I got new opportunity which wants me to join ASAP, 2) The current employers are toxic, which is now taking toll on my mental health. I have tried to discuss with my managers multiple times but they are not understanding and not having much of a discussion. HR has raised hands that only manager can do anything in this matter. The clause that I want to use is as follows : “ Confirmed employees up to the level of and including the Research Manager, may resign from their employment with the Company by giving a two month written notice or salary (basic salary employee is bour plus HRA) in lieu thereof. Employees of the designation of a Senior Research Manager, Senior Principal and above, may resign from their employment with the Company by giving a three month written notice or salary (basic salary plus HRA) in lieu thereof. In the event salary is paid, he might have basic salary plus HRA has to be paid. However, the company reserves the right to expect that notice to be served depending on time required for a smooth handover of the responsibilities of vantage of his the exiting employee.” Currently there are no project I an assigned on and some tasks that I am doing can be transferred to others easily. Also there is no visibility of new projects coming in. They are just holding me in for just in case project comes in since they are in resource crunch (as they say) and can’t hire new folks till sometime.