Restricting an entity by business unit

Hi everyone,

I am new  in CRM enviroment. My CRM is Dynamics CRM 365 Version 8 on-premises.

I want to restrict an entity to all business unit except for one.

There are a lots of security roles in our crm. Most have access to this entity. It takes too much time to remove this entity from all roles.

How can i do show this entity to one business unit?

Thanks everyone.