A weird add pops up?

[Avah123]

I need help. When I turn off my phone and turn it back on instead of getting my password I get a weird pop up thing. It shows my wallpaper and slide to unlock on top there are some apps and below an add for a random game or app. I slide it to the left and says show notifications on lock screen. I can't get out unless I press tabs and it shows lock screen plugin. I don't know how to get rid of it or I don't know what it is I don't have an app called that. Someone please help.

 

[belodion]

Welcome.

Does it persist in Safe Mode?