How to free up memory

Sometimes I need to disconnect and remove huge float array from memory (used in geometry elements).

When I use

[...] parent->removeChildElement(source_with_floats) [...] 

will the array will be deleted from memory or does it just remove the dconnection between parent and child? In latter case how to free up the momory (Im looking for something like delete *float_array; float_array = NULL).