Pruning operations help you maintain a healthy list full of people who want to hear from you. If someone hasn't opened or clicked through your last few emails, there's a good chance they're no longer engaged with your business.
To create a new Pruning Operation:
Go to People > Pruning Operations
Click + New Pruning Operation
Select Count-Based or Time-Based and enter the number of emails or days
Add additional filters with the People Filter
Click Prune People > I’m sure, unsubscribe these people
Those people will be unsubscribed from your list.
Count-Based returns all people that haven’t opened or clicked any of their last "x" number of emails. The maximum number of emails for a Count-Based operation is 15 emails. Time-Based returns people that haven't opened or clicked an email in the last "x" number of days. The maximum number of days for a Time-Based operation is 120 days.
Pruning operations cannot be reversed. Double check your segment before completing the operations.