BlenderKit and file size

Justanewemptyblendfile.blend (547.6 KB) Justanewemptyblendfile-Abotton.blend (2.4 MB) Justanewemptyblendfile-AbottonDeletedbutton.blend (2.3 MB) as you can see from the sizes of the file when I deleted the button from the sceen and resaved the file the file did not get smaller. ?
how do I delete whatever remains from a blend file ? If I download a model from blenderkit but then delete that model why doesn’t the file size get smaller when I delete the models from a blend file ?
There must be a way for me to see inside the file and know what is going on here.