Open Task Manager
Go to the Startup tab
Select the app
Click Disable
Open Settings
Go to Apps
Open Startup
Turn off the app
Open System Settings
Go to General
Open Login Items
Remove the app
Open the app’s settings
Disable launch at startup
Check the app’s preferences for an option like Open at login
Turn it off
Remove the app from startup folders
Delete its shortcut from the Startup folder
Uninstall the app if you no longer want it to run at startup