Creating a Deny User Button

We have an application we would like to use to manage our realm. One of the things we would like to do from this application is deny individual users from the realm. 

I was hoping to create an api button which could accomplish this. Is there an api that denies an individual user? If not, is it possible to deny an entire group and then use the add user to group api to accomplish the original goal?

Any help is appreciated!

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Hannah Wright
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