Can Grim Apothecary bounce itself?

Yes, Grim Apothecary can return itself to your hand.

According to its card text, Grim Apothecary's ability is: "When you play me, you may return a friendly unit at a battlefield to its owner's hand."

Because Grim Apothecary is a unit you control, it is a "friendly unit." Once it has been played and is on the battlefield, it is a legal target for its own ability. When the ability triggers upon being played, you may choose to target Grim Apothecary itself to return it to your hand.