In order to use full machine simulation you need to establish several different things:
establish a machine
choose a corresponding post processor
open a part file that uses the kind of machining done on the chosen machine
In order to use full machine simulation you first need to specify a machine for each setup. Every setup can have its own machine (MD file). You can change which machine is used by the setup by editing the setup properties.
It is important to have an appropriate post processor loaded. So make sure that you've got an MD file that works well with the post processor that you have selected.
Once you've established a machine for the setup, then you can choose Machine Solid Simulation from the View>Simulation menu. Or choose the corresponding button in the Simulation toolbar. Then press play to see the animation.

You should try running the examples that ship with FeatureCAM. In the 'Examples\Machine Design' folder you'll find several folders each containing three files:
a machine design file (MD)
a post processor file (CNC)
and a sample part file (FM)
If you
load the post processor,
load the FM file, and
set the MD file as the machine design file for each setup,
then you'll be able to see full machine simulation.
During a machine simulation you can remove an object from the scene by:
Clicking the select
button.
Clicking on an object.
Note that this just temporarily removes the object from the simulation. It does not delete it permanently.