I just wanted to delete certain transactions from the table after 30days.
Discussion posts and replies are publicly visible
You can schedule a process to start a specific date and time every month and use the "Delete from DSE" smart service to delete the desired records.
Can I trigger that process based on some condition?
Conditions like?
it's trivially easy to set a "cleanup" style process to automatically launch at the same time daily (usually overnight, outside of normal business hours for any / most of your users).