The iMessage app drawer on your iPhone or iPad gives you quick access to things you might want to use while texting, like GIFs, music, location, games, and Apple Pay. If you only want to use the Messages app for texting, though, you can hide the app drawer or customize which apps appear in it. Instructions apply to iOS 11 and later, on all iPhone and iPad models.
How to Manage and Hide iMessage Apps on iPhone and iPad in iOS 11
You can't remove or delete the iMessage app drawer entirely from your phone or tablet. You can only minimize it so that you don't see it every time you send a text, or customize it so that it's less cluttered or better suited to what you want to use it for.
For example, if you don't want sports apps to show up in your app drawer, or weather icons to overshadow the games you like to play with your iMessage contacts, you can hide those iMessage apps from the app drawer.
This is the easiest way to remove the iMessage app drawer. By hiding it, you minimize it so that you don't accidentally tap on any of the app drawer icons.