I have 1.3 million contacts in CiviCRM 4.6.34, but the contacts are outdated. I want to remove all the contacts completely, but cannot find an easy way to bulk delete all the contacts. I also want to upgrade to the latest CiviCRM version because 4.6.34 does not support CiviMobile... Which means I also have to updgrade Joomla from 2.5 to 3.x, which means I also need a new template compatible with 3.x. Anyway, we don't need the 1.3 million contacts currently housed in CiviCRM. We have an updated list of voters (also about 1.3 million) which we will do as a clean import into the newest CiviCRM version on the latest Joomla. I think this makes more sense than overwriting 1.3 million contacts with 1.3 million contacts. Also, we may very well have to pay to migrate our site from Joomla 2.5 to 3.x, and if we have to migrate 1.3 million contacts, it will probably be a rather expensive migration, moreso than if remove the contacts pre-migration. Since we are upgrading everything and need to install a newer version of CiviCRM anyway, will all the contacts be permanently deleted when CiviCRM 4.6.34 is uninstalled? If so, I think that would solve everything. If not, what is the best and cleanest way to eliminate all the contacts? Very little has been done with the contacts since they were uploaded anyway, so I don't believe there are really many (or any) tables to which they are copied on. They are uploaded as part of a 'group,' but otherwise there has been hardly any extra data added in after the fact. Thanks for the help.
welcome to CiviCRM Stack Exchange. As you probably gathered from the comments from @Demerit and @petednz, if you start from scratch with a new version and "just" uninstall and remove the previous version the contacts will disappear from CiviCRM.
It is hard to judge if they will disappear from your website without knowing your website. I do not know if for any reason users were stored in Joomla or other contact data, but you will certainly lose all the CiviCRM data.
The safest option would be to start from scratch, so get a different spot to install your new Joomla and CiviCRM. Then you could just remove your old folders and databases from your webserver once you are happy with the new situation?