How to uninstall hplip and reinstall it - ?
 

How can I completely wipe out (uninstall) hplip?

Then, I plan to reinstall it using the software center which has "hplip toolbox"

Sudo apt-get remove hplip.

How did you originally install it? If it was through the repos then hazel is right although personally I would use purge, not remove. Otherwise the method you used to install should also provide a method to uninstall

I have found that some, if not many, of the hplip versions in repos are not all that good. In getting tailored for specific distros they seem to end up with things left out. For example it used to be that the scan function on all-in-ones did not work if you used the version in the Ubuntu repos. Whether that is still true I don't know since I stopped using those versions long ago.

I strongly recommend going directly to the HPLIP site and download the latest version. In a terminal window change the modes of the .run file to be executable by the user and then run hplip-<version>.run file as a common user, NOT as root. Then sit back, answer questions and wait. It will do all the installation for you, remove any old versions (at least theoretically) and give you a chance to set up at least one printer. This way you know you are getting an installation that works and is not one someone else has fiddled with. It really is just as easy to do it this way as the use the repos.

So you would use Sudo apt-get purge hplip
?

I didn't originally install it, I assume it came installed with the Ubuntu installation.

Yes, I would 'sudo apt-get hplip purge'. That just helps make sure you get the extraneous configuration files or ones the distro puts in odd places that HPLIP cannot find. Then, during installation of the downloaded version you will probably be told that it has found an existing version which might conflict and asked if you want to remove it. The obvious answer is yes.

Thanks!