Is it possible to undefine a variable in ColdFusion?

<cfset StructDelete(Variables, "myVar") />

Variables is the default scope for most variables in most contexts.

In modern versions, you can also use the struct.delete() member function.

myVar = "lsajflksd";

variables.delete('myVar');

https://docs.lucee.org/reference/objects/struct/delete.html