I need more room on my page and the sidebar in my space really bugs me. Can it be made unvisible?
Yes it can, and very easily:
You can expand or collapse the sidebar using the left square bracket ( [ ) on your keyboard, or by dragging it with your mouse to the left or the right.
You can find more info about the sidebar and your space here:
https://confluence.atlassian.com/doc/the-space-sidebar-777010845.html