Can i delete the important.rtf, maserkey.cryptomator, vault

[Michael]

@cryptwo

I was under the impression it might be a good idea to get rid of the older maskerkey backups since those preserve ways to decode the keys using older passwords.

Thats not quite right. (see here)
But you are right, these are backups just in case something really bad happens with your masterkey files. You can delete them if you have backups else where.