How do I turn off teasers?
You have different ways/options to solve your issue.

Option 1: 
Create a page node and then set node URL as default front page in admin/config/system/site-information

Option 2:
Create a view page using Views module and set the page url as default front page (same as previous option).

Option 3:
Download and Enable Empty Front Page module and then locate any block you want in the content region.