How can you really move (not only copy) a mail message from one account to another in mail app?

I have two gmail accounts on my mail app on my imac. The second one is an archive where I want to keep old and less relevant mail messages that I don't want to delete. I'm doing this because there is less than 25% of free space available in the main account.

When you use the command "move to" a mailbox in a different account from the one the message is originally in (main account in this case), the command only makes a copy of the message, it doesn't delete it from the original account. The messages temporarily disappear from the main account, but are not deleted from the server.

You can erase them manually, of course, but that process is prone to errors when you want to move hundreds of messages, because you have to make sure that you are selecting the same messages that you moved (copied).

There is not the option of "cut and paste".

I don't know if there is some setting that you can modify to change the behavior of that command.

Thanks.

(I don't know under which topic should be classified this question)