You have a few options. Let me expand a bit on what some others have suggested, and perhaps chime in with other ideas.
Use a File Manager App
I most highly recommended using a file manager app (not a
download manager app) to locate the files. Not only will it help you in this instance, it will continue to help you manage your device in the future. One of the best and most popular is ES File Explorer. It's free! Another excellent one is Solid Explorer, which is available as a free trial to test out.
When you open the file manager app, it will default to the sdcard or Internal Memory folder view (each app has their own naming scheme).
1. Scroll down to the Download folder and tap on it to reveal the list of files inside.
2. Long press on the file you wish to remove, after which the Delete option will appear.
3. Tap on Delete to permanently remove the file.
If you don't know the folder location of the file you're looking for, simply use the search function within the file manager app.
1. Tap the Search button. (In ES File Explorer it's located at the bottom; in Solid Explorer, tap the Menu button to reveal the search button.)
2. Type in the name of the file. As you're typing, search results will appear, so you don't have to know the entire file name.
3. Once found, delete the file as described above.
ES File Explorer: https://forums.androidcentral.com/e...ls?id=com.estrongs.android.pop&token=0Y3jj5di
Solid Explorer: https://forums.androidcentral.com/e...ps/details?id=pl.solidexplorer&token=UgUG9uuV
Use an Office or Document Editor App
Another option is to use the built-in file explorer function of many office and document editing apps. I won't go into details about how this is done, since each app has their own method, some easier than others. Plus, a dedicated file manager is by far the most efficient way to deal with, uh, file management (who would've guessed?). But if you already have an office productivity app, open it up to explore your options. If you don't have such an app, I'd recommend the free and quite effective Kingsoft Office to start with. A good, paid alternative is OfficeSuite Pro, but there are many other similar, well regarded paid apps available, plus free versions that are for document reading only. I'm not sure if the free, read-only versions have full file management capabilities.
Kingsoft Office: https://forums.androidcentral.com/e.../details?id=cn.wps.moffice_eng&token=dDn30vKL
OfficeSuite Pro: https://forums.androidcentral.com/e...stems.editor.office_registered&token=L51wJ6Bl
Use the Built-in Downloads App
Of course, as primarily mentioned in this thread, you don't necessarily need a 3rd party app to find and delete a downloaded file. Simply go to the All Apps drawer (tap the circle icon with six dots in it, located at the bottom of the screen), then find and tap the app called Downloads. This will open a window that shows files located in the downloads folder. It's not very obvious, but you might need to scroll the list that pops up in order to see the file you want. Then follow the directions given previously by still1.
However, my experience with this method is that not all files are listed there. I'm not sure why this is, but I've downloaded pdf files to the Download folder, and some don't show up in the list of the Downloads app. They are there, though, as they appear when browsing with a proper file manager. Additionally, the list
will show files that are no longer on your device, that were deleted or moved by some other method. When you tap on such file names, a message pops up indicating the file can't be found, and giving an option to delete it from the list, which you should do to avoid future confusion. So, as you can see, using the Downloads app is not the most efficient, foolproof method. Instead, use a file manager app!
Connect to a Computer
Lastly, you can connect your N7 to a computer with a USB cable, then use the computer's file manager (Windows Explorer on a PC) to tidy up your files. After connecting, navigate to the Nexus 7 drive within the computer's file manager, then to the appropriate folder to find and delete the files you no longer want (just as you would do for files on your computer). This is also the most common method for transferring files between your computer and mobile devices.
You can also use the free AirDroid app to manipulate files wirelessly, so you don't have to physically connect it to a computer. You'll use your internet browser on your computer as the interface to interact with your Nexus 7. You don't even have to have your N7 with you after the initial setup. The interface is very intuitive, making transfers and other file management tasks simple. Plus, it offers many other utilities, such as locating and locking your lost N7.
AirDroid: https://forums.androidcentral.com/e...s/details?id=com.sand.airdroid&token=luh6Gs2V
Good luck!