Basically I just need advice on what to do.

My roommate is lazy, doesn't like to contribute supplies for the apartment, and doesn't clean. We have a 1 bedroom apt and he pays $350 for rent while I pay $600. To clarify things, I have the bedroom to myself while he stays in the living room. I know for fact that this isn't fair because I asked for $400 but since he was my only option left, I needed to accept $350. He's a good friend of mine from high school and now we are both studying in the same college. I tried kicking him out after our first semester together but he begged to stay longer because the rent/apartment is really convenient for him. So I am giving him another semester to live with me. Our lease ends in 4 months, so my plan was to kick him out after the lease ends. My name is under the lease too so I have every right to kick him out. **Also my main concern is that I feel like after I kick him out he'll have a spare key to get in and steal my stuff.** Just because we are friends doesn't mean I can entirely trust him with my property. He's just those friends you have in school, he's not a friend that I can hang out with other people.

So how do I kick out my roommate politely?
And should I change the locks to be safe. And if I should, do I have to tell my landlord as well?

Thanks in advance for suggestions.