How to remove magento 2 modules / extensions totally from DB?

You have to delete the attribute which is created from the remove extension(3rd party extension).

Magento saves the attribute basic related at database table eav_attribute.

So you have to run below query for identifying that attribute

SELECT * FROM eav_attribute WHERE source_model = 'MageWorx\SeoBase\Model\Source\MetaRobots'.

You have to delete this attribute from database.

After that flush cache.