There is no way to uninstall just hive by itself. I think at this point it is better to let HMC to install and configure MySQL. Can you please try to remove MySQL and rerun the installer? Please try following:
yum erase hmc puppet
yum erase mysql
rerun the installation per documentation
Once you get to cluster setup url, please don’t put anything for mysql location. Please provide only password. This configuration should allow HMC to install and configure HMC by itself.
Hope this helps.
Please let us know if you are able to complete your installation.