Hi - If someone else is doing the integration, then they should provide whatever is necessary for a successful integration.
As far as resetting Joomla!, not really any "good" way if you have data. All will involve some effort. If there is not much data on the existing site, it is usually better to just start over. As the amount of data increases, migration can get a bit trickier, ranging from exporting the database for possible import into the new site, to cutting and pasting articles from the old to new site.