First question, why do you want to delete them?
Second question, when you say you uninstalled/deleted everything, did that include your content library? Look in “edit/preferences/content library management” (might have the wording slightly out, can’t check it just now as I’m in the middle of a render) if you don’t know where that is.
The files I can see on your screen image are part of Genesis Chablis, however they’re showing in the Smart Content tab, which may possibly mean that all that is there is a reference to a file in the Smart Content database, rather than there being an actual file on disk. If you switch to the Content Library tab then that looks at the actual files on disk instead. From the Content Library tab Chablis should be somewhere under your Studio content, which is the first entry on the Content Library tab, click on it to expand it. Default installation for Chablis is probably under the people/genesis subfolder, but I’ve long since moved mine so can’t be more precise than that. The file names I can see are correct for parts of Chablis, but they should have associated image files - same name, .png extension - which would make them show as an image not a blank file icon - this is what makes me suspect it may simply be metadata that hasn’t caught up with the deletions you have been doing.