How to remove imported messages from Apple Mail

I just upgraded from DTP to DTPO and am going to use Pro Office to archive my older emails however I can’t seem to figure out how to remove them from Apple Mail after importing. I don’t want/need a copy in Apple mail once archived (imported) and am hoping I can do this in one step instead of having to most likely move the messages I want to archive to a different mailbox in Apple Mail, import into DTPO and then delete the mail from Apple Mail.
I know it’s not a big deal but a one step process is so much cleaner.

This will not be automated by us. The reason: we are not able to restore your email to the original format. Therefore, since this is a potentially destructive process, you have to be really aware of what you’re trying to achieve.

Good enough for me. Thanks for the response.