Does'nt you in example have a Factory bank in the left side of the browser window? If you can't see it, then click on the little arrow where it reads "BANKS" to display the banks. You should be able to see it. (Please look in the manual section "3.4. The Preset browser". The BANKS is at the same place as the pictures show TYPES and more.
The imported files should have created at least one bank there.
You can also just delete the folders where the imported presets are located. This is the paths:
OSX: /Library/Arturia/Presets
WIN: C:\ProgramData\Arturia\Presets - ProgramData is a hidden folder, so you have to enable windows to be adle to show hidden folders and files, before you can see it.
If the presets for some reason should not have there own bank/ folder, then you can un- and reinstall DX7 V and be sure all DX7 V presets are removed from the above folder mentioned above, before you reinstall.