Question: Basically I have a few files / folders that I want permanently deleted. I deleted them securely with hardwipe, but when I try to search into the folder where they were located with Wondershare Recoverit, the foldernames, filenames, even some parts the docs/txt's/images are still visible even partly recoverable.

I've tried several solutions, cleaning USN/MFT with programs like Recuvera/Privazer/CCleaner/Revo Uninstaller. I also tried filling up my entire SSD with data, only 100MB of free space left.

Does anyone have any additional programs or an idea how I can prevent specialized programs from finding these folders/files?

Answer: 
If you need the files deleted with any degree of confidence, while still being constrained to continue using the drive, you will have to abandon the possibility of preserving the OS installation that's on the drive now.

From there, you can simply use any disk-wiping tool (for an SSD, **even a single pass** of Random data in something like [DBAN](https://sourceforge.net/projects/dban/) would be sufficient), as long as you do write something ([other than zeroes](https://serverfault.com/a/282583/175102)) to every sector of the drive *without* deleting anything at all between writing the first and last sectors.

You [may or may not](https://security.stackexchange.com/q/41676/26186) be interested in trying the drive's native Secure Erase capability; if supported, it will provide drastically reduced risk of an attacker recovering the data, as well as causing drastically less wear on the drive (a big plus if you can't just destroy it because you intend to continue using it).

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In the future, you should encrypt data at rest that you're likely to need securely deleted. It's much easier to simply dispose of a few encryption keys (especially when stored in an HSM, such as a [smartcard](/questions/tagged/smartcard "show questions tagged 'smartcard'") or [tpm](/questions/tagged/tpm "show questions tagged 'tpm'"), both of which generally support reliable deletion of the keys as a routine operation) than to do all the song and dance required to sanitize a drive, especially an SSD.
Software deletion is not effective. I assume that your hard-drive is a magnetic drive. The best way to delete your files is degaussing.

Next, you can use inbuild deletion commands. Sometimes even those commands also not working properly.

In addition to that, you can use a purging method. It also has some level of data remanence.

In SSD you can encrypt and delete. Then even it is restored, it will not be able to open.

If you have highly secret data, destruction of the media is recommended.