Note that the square heating element is supported by a bracket (red arrow). remove the top screw. Then remove the 8 screws (eg green arrow) securing the oven liner to the base. It's helpful to have a long screwdriver for this. The element can be moved slightly to improve access to the screws.

Using gloves, pull up the liner out of the machine. This sheet metal has very sharp edges, thus use gloves. It will be necessary to bend the sheet metal liner slightly to clear the heater element and the rim (due to a screw sticking out from the bracket ceramic insulator)

The second image shows the liner removed.