take a knowledge base offline or Delete its content

Hello Experts , 

i have an inquiery regarding knowledge managment 

we have a customer requirement , that he need to disable the KM Base of interactions and inicdent, as the customer need the SD agents to use only Doc in the knowledge Lib. and igonre the interaction and incidents Lib. so he like to prevent SD agnets from seraching in it at all .note that this library is full indexed before and users can search in it , 

some how i know how to stop KM Base from bing updated and get indexed . but whatever is exited in it is still searchable 
so i think i need to find a method to take this KM offline , this way it will not select-able in the "search in" option . or at lease to delete the current content in this knowledge base .

any ideas ?