The SQL error is probably caused by "dynamic metas" plugin.
As for the URLs themselves being broken, you should have read the documentation. The uninstall instructions explain to you in detail what options you have to keep the URLs working for a graceful transition period:
4. Uninstalling instructions
If you want to redirect Google SEO URLs back to stock MyBB URLs,
just upload the original, unmodified inc/functions.php, but make
sure to keep Google SEO URL and Google SEO Redirect enabled.
This way Google SEO stays installed and will continue to translate
page names to IDs, allowing Google SEO Redirect to redirect the
Google SEO URLs back to stock MyBB URLs.
This gives users and search engines time to adapt to the change.
To uninstall completely, undo all the changes you made on install,
then go to Admin CP -> Plugins and click 'Deactivate'.
This way the Google SEO URLs will end up in 404 error land.
If you click 'Uninstall' all data regarding Google SEO URLs will
be lost. Old URLs for renamed threads / forums will no longer be
known when you reinstall.