Here are the steps below for performing this task.
Open System Preferences and Click on Users & Groups.
Select under current user (your name on the right). Choose Login items tab. Check startup programs you want to remove. Press the “–” sign below. That is all as shown below.
In the future, you wish to add an Item back, simply select the + button as shown below
Select the “+” and choose the app you’d like add. Then restart your Mac to reflect the change made