Hi Kristen Gastaldo,
Reviewing through your description, it is my understanding you are referring to the following type behavior:
Do I need both of these, if they are both in English?
These should relate to specific English locale/language combinations configured for your instance and can be viewed via the "edit" link to the right of the template. For example:
How do I remove one, if I don't need them?
The red button seen in my screenshot above will allow you to remove unneeded message template locale/language combinations for your instance.
Also, when editing the emails, do I need to edit the plain text AND html? Can I just edit the HTML and the changes will stick?
Yes, you can edit and save changes to the HTML and Text templates independently, however, it will be specific to your email client if both HTML and/or text messages are supported. As such, I would first verify that your mail client supports HTML formatted emails (most do, but your IT team should be able to confirm) before only adding customizations to the HTML templates.
This may seem obvious - but how do I know if I'm using both? We have English and English US. We don't write different emails based on those locations. Do I need both?
For the example provided, modifications to the "English" template would apply to any subset locals (US, Canada etc) unless a specific template is defined at the sub level. So in your instance En:US would override any changes in the En template if your users had their preferences set to English/US:
For more information on message templates you might also find the following sections of the Jive documentation helpful -