In Joshua 10, what did Joshua tell his captains to do to the five captured kings?

Put their feet on the kings' necks

(This is what he told them to do to all of their enemies.)
Joshua called for all the men of Israel, and said unto the captains of the men of war which went with him, Come near, put your feet upon the necks of these kings. And they came near, and put their feet upon the necks of them. Joshua 10:24

After they were done with that, Joshua killed the kings and hung them on trees until the evening.
And afterward Joshua smote them, and slew them, and hanged them on five trees: and they were hanging upon the trees until the evening. Joshua 10:26