How to find (and remove) references to GameObject C#

I want refer to GameObject but it is already been referred to. And therefore it gets referred to several times. I want to find all references to this gameObject and remove them before re-referring again.

How to remove references when you don't know how many of references are there ?

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Simple Example Situation: supose you have two instances of players: the_enemy, and the_doctor. Also i have gameObject the_target_1. At some point during play I refer to the_target_1 in script of the_enemy :

 SelectedPlayer.GetComponent<the_enemy_script>().WhatToShootAt=the_target_1.gameObject;

Than, later at some point, i want to refer to the_target_1 in script of the_doctor:

 SelectedPlayer.GetComponent<the_doctor_script>().WhatToRepair=the_target_1.gameObject;

The problem is that game object the_target_1 still is refered in enemy script.

I actually expected that once refered object automatically nulls all references, but but it does not. What I am looking is something like this:

 the_target_1.gameObject.nullThoseReferencesBySomeMagic();
 SelectedPlayer.GetComponent<the_doctor_script>().WhatToRepair=the_target_1.gameObject;

Thanks for help.

Of course once i find all references I can just go to enemy script and null it from there... but that is not my question. My question is how to remove references without knowing them?