Thank you for your question. I look forward to working with you to provide you the information you are seeking for educational purposes only.
To qualify for discontinued service retirement, an employee must receive specific written notice of a proposed involuntary separation. So, in order for you to apply to Office of Personnel Management for the discontinued service retirement, you need the letter from your supervisors with your intended separation for non-disciplinary grounds. Then you would have to file with OPM. You are also allowed at this point to seek another job in the federal civil service system to transfer to.
If they are harassing and retaliating against you based on a perceived disability or in retaliation for you filing your EEO complaint, then you should not do anything other than continue to fight your EEO claim and subsequently sue them in court if required based on their harassment
and retaliation. You do not want to prematurely take the retirement which could impair your claim for wrongful termination and ability to return to your service to get your full time, since once you take the retirement that is the end of your ability to return.
You have to continue to fight the action based on the retaliation and harassment and see it through, or if your employer is willing to give you a proposed termination without misconduct and you want to walk away completely, then you would contact OPM for the discontinued service retirement.
You could request a transfer to a new assignment in your reply, which would then not impede your EEO and retaliation claims.