There's a friend I have that I'm think of semi-ghosting.
That's not very nice, what makes you want to semi-ghost a friend?
I read stuff about semi-ghosting/slow fade on my favorite blog and I think I should try it.
If you want to end the friendship it's alright but you should tell them the reason. It's rude to ignore someone for no good reason.
Well I'm not going to end the friendship, I'm just semi-ghosting it.
Semi-ghosting them is rude and they will be confused and not understand why you're limiting contact. By doing this you run the risk of ruining and ending the friendship whether it's your intention or not. Most people don't react well to being disrespected and treated like this.