You can have more than one knowledge base on your account. Content can be synced across knowledge bases, but settings (including theme), libraries (files & snippets etc) and reporting is all kept separate for each knowledge base.
To add a new knowledge base, click + New Knowledge Base from your dashboard (you can get to the dashboard by clicking on the owl in the top left of the navigation bar or going to Your Account > Knowledge Bases).
If you don't see the option to add a new knowledge base, you probably don't have another knowledge base available on your account. Click on Your Account > Upgrade to upgrade to a plan with more KBs, or contact us for help.