In here I mistakenly gave bounty to another answer. The bounty should go to xhienne. I clicked on the blue box when it was seemingly clickable (about 10 seconds) but I couldn't undo my action. I ask the mods to please give the bounty to xhienne or allow me to undo my action in some way.
Sorry, this action is permanent. Moderators can refund a bounty before it is awarded, but once it's awarded, it stays awarded.
After awarding the bounty, can I remove it or move it to another answer at a later time?
No, awarding is permanent. (But you're warned about that when actually awarding the bounty.)