I know the password to the RAR file as I locked it myself. Is there a way to do this in WinRAR or an equivalent program? The only thing I knew to do was to extract it, then create a new RAR without the password.
Out of the box, no, you can not. Version 3 of the RAR file format (implemented first in WinRAR 2.9) encrypts the actual data itself, as well as the file headers (if requested) using AES-128 encryption. With just WinRAR, it is impossible to simply "remove" the password from an archive, since the data itself is encrypted with the password.
You could make a quick batchfile implementing a "remove password" feature, which could simply unrar the archive, and then re-compress the files without a password.
Technically, the data is compressed before being encrypted. This indicates that, given enough knowledge of the
RAR file format itself, one could create a tool to AES-decrypt the datastream of the compressed files, and then save it into a new
RAR archive. It should be noted, however, that this requires extensive knowledge of the file format itself.
Given the number of open-source tools that support password-protected RAR files (e.g. unar), one could learn how to do this by reading existing source code, and then using the decrypted, but still compressed, bitstream to generate a new RAR archive. However, this is far from a trivial task, as you would then have to rebuild the RAR header manually as well (or at least ensure the file format's compatibility).
Actually, I think a previous answer from another question already answers this:
You can do it by using this method .
Tools > Convert Archives > Compression > General > Set Password >then click ok and save :)
but it re-compresses the archive.