Android adware lets me opt out: is it safe?
You should absolutely not give them your information or install their app, only bad things can come of it.

You should check in Settings &rarr; Security (or Safety &amp; Privacy) under Device Administrators and remove any that you don't want controlling your device (if present), and then see if you can figure out which app it is and then uninstall it under Applications (also in Settings).

If that doesn't work, try an anti-malware app from a respected company or follow the guide here.  In the worst case, you could also perform a factory reset (in the case of user app malware) or reflash the ROM (in the case of system app malware).