Removing the Quick Launch & Keeping the Global Navigation Bar in SP Online to max Screen Real Estate

Hi,

we have mutiple option to impement the Global Navigation

1) You can use Global Navigation Under (Site Setting--> Navigation Setting) 

2) Term Store, (Follow this linke https://support.microsoft.com/en-us/help/3144166/implement-global-navigation-across-multiple-site-collections-through-managed-navigation-in-sharepoint-server-2013) 

Follow Steps to Configure Global Navigation 

1) Go to Perent Site 

2) Go to Site setting --> Navigation Setting

3) under Navigation Setting Select Structural Navigation

4) Check box on "Show Subsites"

5) Check the Attachment for more information 

6) Click ok

7) Now Go To SubSite and follow Step 2

8) This time you have to Select "Display the same navigation items as the parent site" Under Global Navigation (This will maintain Same Navigation what we have in Parent Site 

Let me know if this will helps or not. 

Best

Sunit Patil 

Skype ID: Sunitonline