Building, integrating, or customizing apps and workflows within Microsoft Teams using developer tools and APIs
Log into power automate
https://make.powerautomate.com/
Go to "My Flows" select the flow you want to remove the message from and then select "Save As" at the top.
The new flow will be turned off by default, go to the new flow and select "Turn on". The copied flow will no longer show the part of message you want to remove as it's not using a template.
Be aware the new flow will have a different URL so you will need to use that instead of the URL from the original flow. Once the new flow is working you can delete the original flow.