File in Trash cannot be deleted, not even with sudo rm

Ever since Dropbox updated its software a few months ago, and advised all Mac users to update in order to continue having the same facilities, a folder in my Dropbox Cloud was apparently corrupted and could not be read. I tried to salvage what I could and deleted the folder directly from the Dropbox site. It, however, appears in my Trash and cannot be deleted. I get: "The operation can't be completed because the item > is in use". (All other items do get deleted from Trash.) I have tried sudo rm commands from Terminal, using all possible parameters (-R, -ri, -rf etc.) to no avail. I have tried to erase it *before* Dropbox gets loaded at startup, again to no avail. I have erased ".Trash", but again the stubborn file pops up in the Trash. I am using MacOS Monterey 12.6.6 on a Mac Pro (Late 2013). Help will be much appreciated. Thanks.