You encounter the error "You do not have permissions to do this" in one of the following situations:
- When you are creating an email template, you click on the Validate HTML button
- When you are trying to edit an existing email
If you are unable to actually edit the asset, the workaround is to clone the asset. If you clone the email, it can open in the editor and then you have the ability to remove the script. After this, the email will be good to go.