why wont my lock screen let me press none its grey

[AC Question]

I put a pin on my lock screen and now it won't let me put none back on there its all grey but the pattern pin or password buttons isn't

 

[B. Diddy]

Welcome to Android Central! Which phone? Did you encrypt it? If so, encryption requires the phone to have a PIN or password. Also, if you have a corporate email account on the phone, your company may have required the phone to have security credentials that require a PIN or password.