How can we remove the Help center link for different brand in the password recovery emails?

We have 5 brands under Zendesk. Yellow brand(for reference from the screenshot) is our main brand/used for our company's users. Red brand is used for all our partner company's users(whitelabelled clients). We created the red brand to mask all the yellow brand branding from our red brand users. 
If we sign up from the Red brands Help center as an end user, we can still see the yellow brand's Help center link. How do we remove this? 
It defeats the entire purpose of having a different brand.