How does ransomware delete the original files in such a way that they are unrecoverable?

Ransomware encrypts the original files using strong encryption algorithms, making them inaccessible without the decryption key. After encryption, some ransomware may securely delete the original files to prevent easy recovery through techniques like overwriting the original data with random values or using secure deletion methods, making it nearly impossible to recover the files without the decryption key. This is done to ensure that victims are more likely to pay the ransom to regain access to their files.