By default, games running on touch devices will have two virtual joysticks (like a console controller). You can change this in your Project Settings, in the Input section, with the Default Touch Interface property. This points to a Touch Interface Setup asset. The default one, DefaultVirtualJoysticks is located in shared engine content (
There is also a Left Stick only version, LeftVirtualJoystickOnly, for games that do not need to turn the camera.
Note that you will need to check the Show Engine Content checkbox in the object picker View Options settings to see these.
If you do not want any virtual joysticks, just clear the Default Touch Interface property. Additionally, you can force the touch interface for your game independent of the platform it is running by checking
Always Show Touch Interface (or by running the PC game with -faketouches).