Sphere is created from 3D geometric objects with the Sphere command.
Location of Sphere Command
You can access it under the ribbon menu Home tab Entities title.
Click the Sphere icon in the ribbon menu .
The 3D Geometric Objects toolbar will open.
The first point you give will define the center of the sphere.
The 2nd point created by moving the mouse or using the coordinate box will determine the radius of the sphere.
The sphere object will be created with the 2nd point.
Creating the first point (center) of the sphere
Creating the second point of the sphere (the point whose radius will determine its value)