Inhumans was originally announced when Marvel hosted an event announcing their Phase Three lineup back in late October 2014 when it was slated for a 3rd November 2018 release. Since then it was moved back to the 12th July 2019 and over a week ago it was removed completely.
Speaking with Collider earlier in the month, Kevin Feige said:
Since we made our initial phase three announcement, we added Spider-Man, which was a big joyous coup for us. We added Ant-Man and the Wasp, which was a big fun continuation of that story for us. Walt Disney Company has announced an Indiana Jones film for right around that same time. So I think it will shuffle off the current date that it’s on right now. How far down it shuffles, I’m not sure yet.
As Feige stated, since the announcement we’ve seen Spider-Man and Ant-Man sequel (Ant-Man and the Wasp) added to the slate, pushing Inhumans back to the point it was released just a week before Disney’s Indiana Jones film so it makes sense to just remove it completely for the time being and maybe use Inhumans as a launchpad for Marvel moving forward with Phase Four after the Avengers: Infinity War films. In the Collider article in relation to the news I wouldn’t think that this was removed due to how heavily influenced Marvel’s Agents of S.H.I.E.L.D has become using the Inhumans on the show as Kevin Feige even says that the studio still planned to adapt Inhumans for the big screen, it just “a matter of when.”