I'm baffled, this is a hilarious workaround.
That said,
1) I too had a stupid sim put down her mug 'outside', I then realized the mug could not be removed. However it eventually disappeared. I play in rotation and regularly clean caches (including the lot caches most people seem to ignore). On next rotation it wasn't there anymore.
2) From what I read the object set as head is fully usable by your sim wearing it - leading to fun animations if your sim takes a bath in his head tub for example - so why reset your sim to put it down - and be stuck with an unwanted trashcan? i.e. have you tried it directly?