Best way to remove unwanted leads
When we first imported our leads into Marketo, we mistakenly brought over everything in our Salesforce database which contains almost 20,000 leads. Since I only engage with about 5000 of those, I'd like to remove them from the Marketo database. Anyone know of a simple way to only delete leads that have never engaged with us and keep everyone that has an activity with us? The other reason we need to remove these leads is we are way over the 10,000 lead count for our subscription.
Thanks for the help.