How to uninstall this module?

Why would you want to uninstall this beautiful module? What harm has it done to you? ;-)

As any Drupal sitebuilder will tell you, you cannot just delete the module folder and expect DEPENDING modules to continue to function.

So you need to download that module folder again and put it back where it was.

Then visit the Modules page, admin/modules to disable the module after you've disabled the modules that require it, which in your case most likely is just the "Views Global Filter" module.

Then after saving the module configuration click the UNINSTALL tab on the same page. This will make the module clean up after itself, i.e. it will remove from the database stuff no longer needed.

After that you can safely remove the session_cache folder.

Rik