it also imported some tables that are not required as the modules we uninstalled
Actually, this is normal and is good.
Here's why: Let's say you are using a particular module that needs its own data tables to run.
Now, a new version of that module comes out and you want to upgrade to the "latest and the greatest."
The normal process to upgrade a module is to uninstall the module, then install the new version. If the tables were dropped completely when you uninstalled the module, then you would have to totally reconfigure it when you install the new version.
But, by leaving the tables in place, reinstalling the new module is a much, much easier process!
So, this is actually a good thing and is by design.
Some module uninstallers give you the option of "totally uninstall, including removing the data tables" while others just leave them behind thinking, "Right. This webmaster is probably just upgrading our wonderful module."
So, if you are sure that you don't need the tables any more, and you are sure you know exactly what tables are used by the module (it's often clear by the table names), then you can drop the tables from the db in phpMyAdmin.
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