Close an open email activity without actually sending the email

HI all

Our organization sometimes enters "memo" emails after the fact to include "recipients" since Set Regarding can only be applied to one entity and one record.

 IS there a way to "close" these open emails without sending them?  I read somewhere you could use SaveAsCompleted() but I'm not sure how to do this, or if it's supported, or if there is another, easier way.

thanks