hi @Quentin_Morel , to start with your last advice. That seems the way to go for me: do not delete but hide.
anyway, @Duy_Nguyen asked us to help with a delete. it can be done in various ways like the one described very well by @Quentin_Morel . What I like about the question is the honesty related to ‘all rows’. What the software does is indeed running over all rows, but it is up to us to tell the software what to do with each row. We are in control 
Below my take on it.
- table with checkbox and column that contains the last change
- checkbox that only gets active when there is a delta of 30 days and the update is checked
- automation that runs
here it goes
next we add a rule that is only active when the date is 30 days in the past and the checkbox is checked. Two conditions have to be met. Since the function does not allow for manuel manipulation, I added a test column to show you how it works.
the last step is to have the automation run over all rows, but to only delete the rows with the checked values and for the latter we apply a filter:
This is not a better way, simply an other method.
Enjoy the variations and flavors we bring to the table.
Cheers, Christiaan
ps I documented my contribution: