Changing the Office 365 Logo In Sharepoint Online 2013 Sites

022014_0452_changingthe1To brand the top bar navigation with your own logo and hide the Office 365 one, add this to a site stylesheet:.o365cs-nav-leftAlign {background:#000url(YOUR_LOGO_URL_HERE) 0 0 no-repeat !important;}.wf-o365-o365logo{display:none !important;}
Change thecolor to match the theme you’re using.
Change The Link
To change the link, add a div to your master page with the o365cs-nav-leftAlign class. Insert your desired link in the div. Then add a position to that class:

div.o365cs-nav-leftAlign {position:absolute;top:5px; background:#000url(YOUR_LOGO_URL_HERE) 0 0 no-repeat !important;}
Change Other Top Bar Links

Use the same technique to change links like the sites links, making the appropriate adjustments to account for the different location. If you want to simply hide or adjust the style of other links, use a browser inspector tool to identify the link’s id/class and then add css code to target it.
For example, to hide the “OneDrive” link, add this to a stylesheet:
#O365_MainLink_ShellDocuments{display:none !important;)