Yes, you can remove imported emails at any time.
Imported emails are essentially copies of the original email. Once imported, you can delete emails from the original account (ie Yahoo). You can also remove imported emails from your Helm account as you would any other email account.
Please note that if you delete imported emails, they will still exist in the original account (ie Gmail) unless you have deleted them there as well.
If you have deleted emails from the original account and then later perform another import to Helm from that account, new emails will be imported over. Emails that have already been imported will not be duplicated, and emails that were deleted in the original account will continue to exist in your Helm account if they had previously been imported.
For any additional questions or clarification, please reach out to our support team.