I haven't been working with Joomla for a while, so forgive my stupid question. I just cant figure it out at the moment.
Here it comes:
How does one delete (or enable) the left side column in a joomla template (Replicant)?
You have to disable all modules that are set in this position (this should be 'sidebar-a').
The other solution, if you don't want this sidebar for a specific page, is to not display the modules set in this position for this specific page (menu item).
Everything can be managed from the module backend.