No reason to seek him out to tell him to go away, just wait for him to call again (and he will) and then tell him, over the phone that you aren't interested any more in the FWB thing and you're no longer available for uncommitted hook ups. Then wish him well and hang up. Don't argue or defend your stance and don't be available for him to come over where he can talk you into "just one more booty call". He's not your BF, so he doesn't deserve the formality of a face to face break up.
If he turns up on your doorstep unannounced or uninvited then do not let him in. And tell him to his face that you aren't interested any more in the FWB thing and you're no longer available for uncommitted hook ups. Then wish him well and close the door in his face. Don't argue or defend your stance to him. don't place yourself in a position where he can talk you into "just one more booty call for old times sake." He's not your BF, so he doesn't deserve the formality of being invited in to break up in private.
We all make this mistake at least once in our lives. We buy snow job about how special we are and how much he has always liked us when all he wants is to get in our panties and move on to the next one.
You have to know what you want going into a relationship and you have to be strong to make sure you get it. Players will do their best to wear you down because the thrill is in the chase and attaining the unattainable. and once you surrender to a player, they know they can get you to give in to them again. Think of them as the cute little puppy dog begging at the dinner table. If you feed the dog once, then he's going to beg everytime and keep it up until you give him what he wants because he knows you've done it before. but if you don't give in to the sad little puppy eyes, then eventually he'll go away and leave you alone. He doesn't try as hard. He'll still beg but he gives up easily and moves on.
If you want a playmate, then play. enjoy the play for what it is. a physical release that is slightly more engaging than going solo. enjoy it because it's fun but don't add any meaning to it beyond the pure physical.
If you want a partner, then save sex for when you are an exclusive couple and not a second before.
Playmates almost never become partners and partners hate to become playmates. Never confuse the two and you won't lie to yourself and set yourself up for this kind of disappointment again.