Normally, you only have to reboot and it will go away. The last time I did this, I lost a lot of configurations, make sure to cycle through all your apps and settings.
Safe mode is accessible by by long-pressing the "Power off" soft button and accepting to go into safe mode. You can also boot to safe mode by holding both volume up and down while your device boots.
Google "Android safe mode" and you will have all the information you need.