How can i disable startup programs when mac boots?

Hi, Anthony, you can remove startup items manually on Mac. Go to System Preferences>Users & Groups. You will see the interface as below. Choose the current user and tick the items in the left tab to hide them or select the one you don’t want and hit the - button.

And you can disable startup programs with third-party tool, it scan out more startup items that affects your Mac startup time. So I recommend you to use the software to disable startup programs thoroughly.

Also, when you Shutdown, make sure that you uncheck the box that says, "Reopen windows when logging back in."

In System Preferences > Users & Groups > Login Items remove those item you do not wish to have start at login.