As per title, I am struggling to work out how to achieve this. As you can see from my screenshot, I am trying to remove the bit in the bottom right hand corner. In the Edit Themes area, it seems you can only edit the code for the survey themes, and not the admin themes - I am using the Bootswatch theme,
Below screenshot is the admin page (before we go into a survey)
I would suggest not do that.
When someone needs help with installations, we're always asking them first to provide their build number which appears in the footer.
Why do you want to remove it?
Well, I assume he/she wants to "white label" Limesurvey, so their employees (or clients) don't know it is Limesurvey. In this case they probably also don't want them to ask here in the forum, but rather give support themselves. Given that they struggle to remove the footer, probably still not a good idea.
I answer at the LimeSurvey forum in my spare time, I'm not a LimeSurvey GmbH employee.
No support via private message.