Click the "X" icon on the main screen's Toolbar with the Table(s) selected.
Click "Edit -> Delete" from the main menu.
Use the keyboard command "Ctrl + D" or "Delete" from the main screen.
Right Click the Table in the main screen and select Delete.
Deleting a Table may have potential affects on several other objects in the Schema.
All Constraints and Indexes that reference the Table will also be deleted.
A View which references the Table will remove the reference.
If that View's last reference is removed, the View will also be deleted.
Due to the free text nature of Functions, Stored Procedures and Triggers, references to deleted Table's will not be removed and are your responsability to fix.