Q: I would like to delete an apple id permanently while merging its assets to my main ID . Is this possible?

You can't delete an Apple ID from the server, though of course you can just stop using it. However you cannot transfer purchased items from one ID to another. If you have two iCloud accounts you can transfer data from one to the other, but you will have to do it manually via your Mac and it's something of a pain. You can't move email addresses or aliases from one iCloud account to another.