Hey @popiinyourpocket 

Welcome to the community, sorry to see you are having a challenge with your flow. Happy to help.

Depending on your management user role, you will have different access and permissions within the platform that may prevent you from deleting a flow. I would first check you make sure you have the appropriate permissions.

Next, a 403 error code usually means that its something going on with your browser. Typically if you clear your browser's history and cookie cache and then completely restart your browser, it usually resolves itself.

However, the bigger question is if the flow is in draft mode, why is it still sending to your customers? Can you share a profile where the flow in draft mode has been sent to your customers with your old logo/design? This should not be the case and will need some investigation if your customers are receiving marketing from your brand that is not set to Live. 

Hope this helps. Thanks again for being part of the Klaviyo community!