how can i delete a video sent via iMessage from my iCloud account so that it won't show to new devices i log into?

Hello D.Costa,

Thank you for contributing to the Apple Support Communities.

It sounds like you sent a video using iMessage on your iPhone, and you want to delete it from iCloud.

If you are using iCloud Photo Library beta, use the steps in the "Delete photos and videos from iCloud Photo Library beta" section of this article to delete the video:

iCloud: Use iCloud Photo Library beta on your iOS device

If you see the video in your Photo Stream (also called shared stream), see the steps at this link to delete the video:

iCloud: Delete photos or videos from a shared album

Best Regards,

Jeremy