This is very simple, but I feel like a lot of people want to do this and overlook this method.
Note: This will replace the head with a default head and a default face (I think) no matter what you’re already wearing, but if you just want that and you don’t care about matching the old 2d faces with each new 3d one, then this is your guide.
Simply go into Avatar Settings, Custom Parts, and check off the Head part AND LEAVE THE ASSET ID BLANK
Then click Save Changes, even though it will say “Asset does not exist”
Before:
After:
And Roblox, if you’re seeing this, please don’t make this tutorial null and void nor make this method not work, I have a game that gets around 1.5k players on weekends and a 98% like ratio that relies on having a blank face (which it used to achieve by just removing the head decal), so this method is important to how the game works. If you plan on “fixing” this method Roblox, please at least allow me to force 2d faces into all avatars in my game. Thanks.