Can't react on other topics and can't find the solution

Hello,

I’m asking this question because I find similar questions but without a explained solution.
I’m using the home v9 and imported the demo page. Every time I remove a couple of existing columns the footer isn’t showing full width but smaller and overriding a color section, in this case a video background. I took some screenshots but I can’t attach them if i’m correct.

Can you tell me how to fix this?

Looking forward to hear from you.

Best regards,

Gerard