The addon product to which those phrases belong should be removed when you uninstall the product: Admin CP -> Plugins & Products -> Manage Products -> Uninstall (in each product menu).
If the uninstall process didn't remove the phrases then it's a problem with the product's uninstall process in which case you need to contact the author of that product.
*In some cases you can review the .xml product file itself and determine the newly added phrases, utilizing the phrase manager you can manually update these to remove the standard text etc, if you simply try to save it w/o a value it will not save over the previous data instead add in a commented out line.
**Please be sure to check the Plugin Manager: AdminCP > Plugins & Products > Plugin Manager for plugins related to the modification you uninstalled, ensure they are disabled. You may delete plugins related to a mod that did not correctly uninstall howeve if your unsure the best course of action is to simply disable.
