Instructions: How to Disable the extension in your Joomla database.
1) Login to your Control Panel.
2) Click on Websites & Domains.
3) Select Databases.
4) Click on the name of your database.
5) Under the Tools menu choose Webadmin to open phpMyAdmin.
6) Locate the *_extensions table. The full name will be something like ufhi_extensions depending on your database prefix.
7) Locate the row for the extension you attempted to install and click on Edit.
8 ) Change the enabled field from 1 to 0 and click Go at the bottom.
After I disabled the plugin, I noticed a bunch of database errors. Then I went to the Manage Extensions Area and uninstalled the Favicon Extension.
After all these things were finished, everything went back to normal. I am running PHP 7 and Joomla 3.6