If you're confused by the above directions, or for some reason Discord continues to start up automatically when you open your computer, then you can change its startup options in your computer's settings instead.
If you're using a Mac computer, you'll want to start by clicking the apple icon in the upper left corner of your home screen and select "System Preferences."
Go to "Users & Groups" and then select your profile. Choose "Login Items" to see what apps automatically start up.
From here, you can select the apps, like Discord, and then click the minus button at the bottom. This will remove the item from automatically starting up when you turn on your computer.
If you're using a Windows computer, you can also change this in your computer's settings. Go to your Task Manager. Once you've opened this application, click the "Startup" tab to see what applications have startup "Enabled" when you start your computer. In this list, right-click "Discord" and then select "Disable."
Once you've done these steps, you shouldn't have a problem with Discord automatically opening on your computer when you start it up. If you're still having a problem, try restarting your computer or contacting Discord support for more help.