Re: email attachments flow auto delete attachment from outlook after syncing to onedrive
Hi @ zheidemann,
Do you want to save all attachments from outlook to onedrive and then deletes the attachment from outlook?
You could create a flow to save all attachments from a folder(Such as Inbox) in outlook to onedrive currently refer to screenshot below:

Note: There is a limit in the amount of emails that the “Get emails” action retrieves, the “Get emails” action could only retrieve at most top 25 emails once, if your original "Site Alpha" e-mail is not in top 25 emails, the “Get emails” action would not retrieve it.
Do you want to delete all the attachments from outlook?
If you would like to delete the email which has attachment, Microsoft flow support to delete a email currently, you could add a "Delete email" action under the "Apply to each" and refer to screenshot below to create the flow:

If you only want to delete the attachment and don't delete the email, delete the attachment and don't delete the email in not supported in Microsoft flow currently,I afraid that there is no way to achieve your needs in Microsoft Flow currently.
If you would like this feature to be added in Microsoft Flow, please submit an idea to Flow Ideas Forum:
https://powerusers.microsoft.com/t5/Flow-Ideas/idb-p/FlowIdeas
Regards,
Alice Zhang