Hi there are a few places to look, it depends on if the file is a "Scheduled Project" or a "Scheduled Report" (the distinction being that a Project is a Workspace Project vs a Report being a Legacy Report or Report Builder Report)
If it's the first (i.e. a Workspace Project), you should be able to find it under Components > Scheduled Project
When you click on the project name here, it won't open the project, but will open the scheduler for you to modify it.
If you are talking about a Legacy Report or Report Builder report, the direct link has been removed from the menu to simplify it, but it's still available. If you click on Components > All Components, this will take you to a page listing all Component links. Here you should see something called Scheduled Reports.
For Report Builder Reports, I believe you can also adjust the schedule via the Report Builder plugin.
Hopefully this helps you find what you are looking for.