The owner of the file is shown at the top. In the properties dialog that appears, switch to the “Security”-tab and click on “Advanced”.
To do this, start by right-clicking on the file or folder and selecting “Properties”. As administrator you can set yourself as the owner which is called “taking ownership” in IT-lingo. Some files/folders cannot be deleted by you as a user because another user is marked as owner. If someone else is managing your system as an administrator, you will need to contact them. If your user account does not have administrator rights, you will need to log in with an appropriate admin account. The most common reason why you cannot delete a file is lack of user rights on the system.
Method 1: Delete file/folder as administrator
With the following 3 methods you can still get rid of such files or folders. In some cases such files remain “marked” as open / “in-use” or you simply do not have the user-rights to delete them. This might be quite annoying if you definitely don’t need the affected files/folders anymore, like in the case of files that had been used or created by an already uninstalled or removed software.