If someone accidentally puts hand dishwashing liquid in the automatic dishwasher, the result is a tubful of suds which seem hard to get rid of. Fortunately, there are a few techniques which work well.
Sprinkle ordinary table salt liberally across the suds to disperse them. Add a large quantity of ice cubes from your freezer to the tub. This causes the water temp to lower, thus degrading some more of the suds. Try to drain the unit as much as possible, soaking up any residual water or suds with a dry towel. Let the unit fill again, and repeat the salt and ice if necessary.
You can also use a commercial spa defoamer, which is found at Home Depot or any pool supply store. This works as a surfactant to break down the bubbles almost instantly. (Only squirt a few drops in and run the unit)
A third method is to add a capful of Downy Liquid Fabric softener to the tub
and let the unit run a few seconds before selecting the drain cycle. Downy
will break up the suds and allow them to drain off.