mop up the floor with - Phrases/Idioms
The American Heritage® Dictionary of Idioms by Christine Ammer. Copyright © 2003, 1997 by The Christine Ammer 1992 Trust. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Also, wipe the floor with. Defeat thoroughly, overwhelm, as in The young boxer said he was sure to mop up the floor with his opponent, or I just know we'll wipe the floor with the competition. [Late 1800s]