Releases a drawing object
(vlax-release-object obj)
When an AutoLISP routine no longer uses an object outside AutoCAD, such as a Microsoft Excel object, call the (vlax-release-object) function to make sure that the associated application closes properly. Objects released with (vlax-release-object...) may not be released immediately. The actual release may not happen until the next automatic garbage collection occurs. You can call (gc) directly to force the garbage collection to occur at a specific location within your code. However, calling (gc) may degrade performance, and it is recommended that you avoid placing calls to (gc) in locations where it is likely to be called many times in a row, such as within loops.
If an object-associated application does not close after calling the (gc) function, the (vlax-release-object) function was not called for all objects outside AutoCAD.
After release, the drawing object is no longer accessible through obj.