That tin piece is called a Baffle and it help to keep grass from entering the bottom of the motor as well as protecting the flywheel and the ignition which is underneath the motor.So removing,I think is a bad idea.It does sound like you haven't got it on correctly.There are 2 lugs on the head side which should go up under the head to help hold it on.Then it lines up with the bolt holes.I'm not sure if it can fit,but maybe it's around the wrong way.I did at one point have one that was a mongrel to fit as every-time I got close the 2 lugs for the head end kept coming out.I'd dare say that's what wrong with it.
So no don't remove it,it is there for a reason.See if those lugs are under the head like they should be.
Let us know how you go.
