It is recent, not resent (sic), and only will appear on the bottom of the Safari Share menu toolbar item if one shared a web site via the Mail sharing menu selection.
These entries are stored in the ~/Library/Preferences/com.apple.sharekit.recents.plist as part of a massive Array of dictionary entries, and in my case that is 100. Since one would have to peak inside each of these array elements, and its dictionary content to determine if the recent item from the first sentence was contained in that array's dictionary element, and if it in fact was used for Mail sharing, or some other sharing functionality — cleaning the Safari Sharing Tool's Recent entries would be significant work.
In the case of names appearing in the Safari Sharing Recents list, there are two entries contained in a dictionary for each array element in the preceding image, as well as another array and separate strings and a number.
/usr/libexec/PListBuddy -c "print :SHKRecentServices:n:parameters" ~/Library/Preferences/com.apple.sharekit.recents.plist
n = dictionary element shown as Item 0, Item1, … and parameters is another dictionary.