Hi there!
You can remove the existing login button with the following CSS:
#sp-header .btn-outline-primary{
display: none;
}
Then publish your module to the menu position and then style it to set up in a good looking way.
Or,
You can create a custom header with what and how you want to see your header. And you can publish your module to your desired position.
Here is how to create a custom header:
https://www.youtube.com/watch?v=bYPgWAWzXpM
Note: Customization support is prohibited here!
Hope this helps anyways!
Best Regards