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Yes you can uninstall
To uninstall a module you go to system admin/modules, and remove the checkmark to the right of the module and then "submit" near the bottom of the page.
Next time you go in to this page an uninstall icon will appear next to the module. Click this and it will uninstall the module, deleting the database entries etc. Then remove the files for the module from the "modules" folder on your server.