There are no automations in glide. Everything is controlled through user activated actions.
I’ve recently implemented a process to “archive” rows in a table (in my case I change the row owner email so it is no longer owned by anyone). A similar process could be done to delete rows. Right now I archive one row at a time. I talk more about it here.
A similar method could be used to delete rows instead of marking them as archived.
Recently Glide opened up the option to delete multiple rows at once through a relation. What I think you could do is create an action somewhere in your app, so when a user clicks a button or views an item in a list, you could perform the delete action. All you need is a relation that only links to rows that are more than 30 days old, much like what I did in my app. In my case, it’s anything older than 2 years. You would just need a math column to find the number of days between now and a date on your table, then an of column to return ‘true’ or some other value if the number is greater than 30, then in whichever table would be used with the action, create a template column with the word ‘true’ and build a relation linking true to true.
It’s not automated, but with the user simply using the app and calling the action, it will be the user that initiates the delete.