I am a newbie to Ubuntu and have used it for less than 3-5 months. Am using Gnome 17.04 and intend to install 18.04 LTS or a higher Studio version. Not sure how to switch the flavour. Can anybody help me on that? This ideally should be without uninstalling the original installation?
Else tell me how to remove the old one and put the new one?
Switching from Ubuntu GNOME 17.04 to another distribution and skipping over a release when upgrading will be difficult to do successfully. Waiting until 18.04 is released in April, 2018 and making a clean install is clearly the easiest way to do it, and it will save you a lot of time and wasted effort in the long run.
To install a new release over an old release follow the instructions in How do I reinstall Ubuntu?. Because you are installing a different release I recommend backing up the personal data in your /home folder, and then when it comes to the Installation type section of the Ubuntu Studio installer select the option to overwrite the existing operating system and replace it with the new one. Selecting the first option, Upgrade Ubuntu GNOME 17.04 to Ubuntu Studio 18.04, may not work properly because you would be skipping over releases when upgrading.
sudo apt install xubuntu-desktopor what have you or you can try them live or on vitrualbox . Once you decide what you want to install (KXStudio , ubuntu studio, kubuntu, whatever) just install over the top of your current install, no need to remove anything, just understand your partitions is all. I agree, although I tend to upgrade rather than fresh install, with all the changes to Ubuntu, I would fresh install any version 17.10 or higher . Waiting for 18.04 is probably a good idea. – Panther Oct 17 '17 at 14:46