I have an 18 year old son that lives at home with me--He smokes pots all the time..?

He dropped out of high sch ool-and doesnt work..He has a bit of a learning disability--and could have attention deficit..which explains why he might smoke pot--Yet he refuses to live by MY rules--HE MOUTHS off to me......CALLS ME NAMES>.and tells me to shut up- I have asked him to MOVE out many times and get his act together..BUT HE REFUSES.......how do I get him OUT? He needs to grow up and quit taking from me.....???