Help i cant get rid of this app

Okay. So I accidentally downloaded some stupid thing that puts pop up ads on my phone. I found the app in question, however I cannot uninstall it as it is a device administrator. I went to settings>security>device administrators, but the app has the ability to lock my screen, and will do so when I try to deactivate it.

Welcome to the forums. Boot into safe mode and repeat all those same steps to deactivate the app. Tell us how it goes.

Also, did you download this from the Google Play store? If you did, you should report it.