Please help me in release process. Should I send a mail to HR,ProjectManager & DeliveryManager or should I first approach project manager,HR

Why do you want a release from project in such times, stay where you are.

You can put down your papers. Taking or asking for release is a dangerous situation to be in. They may just take it to their ego and try doing whatever they can to make your life miserable and then drop you.
Since you have mentioned toxic, if you are okay with lay off then just drop your papers and jump ship. Its better than trying for release then getting ass whooped and back stabbed with a forced resignation or termination. Worst case they may even not give severance or pay little and give shitty LOE.