Trying to lose 10 pounds in 10 days you're essentially just trying to cheat the scale.
Theres no way to lose 10 healthy pounds in 10 days.
Because even if you do it, you did it to meet a deadline and as soon as that deadline has passed the lifestyle that helped you acquire those 10 pounds in the first place is going to gift them back to you.
Now, I have no problems regarding cheating a scale to win a bet at work. As a matter of fact I fully endorse it. I think its the best way to show up your coworkers.
So lose the water weight or the cleanse weight and win a free dinner at Fatty McFrys or whatever the prize is.