The suffix of "unmanageable" is "-able."

The word "unmanageable" is an adjective meaning "difficult to control."

i.e. "The high humidity rendered my hair unmanageable"

The meal was unmanageable.

This team is so unmanageable that I have to fire them.

Example sentence - We are demanding you keep your mangy unmanageable children at your home as they are no longer welcome in our home.

The word unmanageable basically means that someone will not listen to directions. They are difficult to mange because they do not like being controlled by someone else.