Microsoft, by design, released many features on the new SharePoint sites on Office 365.
One of these features is a footer for the Communication sites.

But if you just have a footer in your design or you want to add another footer, you can easily remove the default functionality with a simple script.

First of all, you need the latest version of PowerShell PnP.
You can install it with the following command from a PowerShell terminal instance:

Install-Module SharePointPnPPowerShellOnline

Now you can run the following script to disable all footers in all Communication sites.
Remember to change the first variable with your tenant name.

The script automatically retrieves all sites filtered by the Communication site template and disable the footer.

You can find the script on my Gist account:https://gist.github.com/kasuken/70e3cabd073f652006726f5968136c0e