I have an O365 SharePoint root site at xyz.sharepoint.com. Can I safely remove the root site in O365 Admin Center and recreate a new root site and even change the address to abc.sharepoint.com?

If I remove the existing root site, will there be after that the root address field available without /sites/ directory name?

Hi,

for the hosted aspects of O365, you may find broader audience here:

http://community.office365.com/en-us/f/default.aspx

Or, for SharePoint Online: https://social.technet.microsoft.com/Forums/office/en-US/home?forum=onlineservicessharepoint