Delete the reference MEMORY

I'm not sure wha you want to achive, so I ask a puzzling question: do you want to create dungling object? "I want to remove the object from memory even if it is still referenced in memory", as I understand, would free the memory used by an object but let the object referenc(es) intact, so the reference now would point into nirvana. Is that what you want to do? Why? Can you a little bit elaborate, what is your target or the background respectively?

> I want to remove the object from memory even if it is still referenced in memory  
That makes no sense and it is not possible, it would invalidate every other variable or object property that references it.
But why do you want to do this?

Just for the case, you are lost in the working memory space and desperately searching the spot(s) in your programm where a specific object is once again referenced, here a small handy method which could help you

/// find all variables which contain a given object(reference)
/// 
/// I: the OREF you looking for
/// 
/// O: "" if the spool-device can't be opened
///    [] if no variables contain the given OREF
///    [var1, var2, ... varN] an array of variable names (incl. subscripted and orefs)
///    
ClassMethod FindObject(obj)
{
	set res=[]
	if $d(%)#10,%=obj do res.%Push("%")
	new % set %=obj kill obj
	
	lock +^SPOOL("nextID")			// adapt this lines
	open 2:($o(^SPOOL(""),-1)+1):1	// to your method of
	lock -^SPOOL("nextID")			// creating new spool IDs
	
	if $t {
		use 2
		set spl=$zb
		do $system.OBJ.ShowReferences(.%,1)
		
		for i=1:1:$za-1 {
			set x=$p($zstrip(^SPOOL(spl,i),"<=>w",$c(13,10))," ",3)
			do:x]"%.~" res.%Push(x)
		}
		close 2
		kill ^SPOOL(spl)
		
	} else { set res="" }
	
	quit res
}
ObjectScript
ObjectScript

Example

USER>kill
USER>set pers=##class(DC.Person).%OpenId(1)
USER>set temp=pers, zz(3)=temp
USER>write ##class(DC.Help).FindObject(pers).%ToJSON()
["pers","temp","zz(3)"]

ObjectScript
ObjectScript