Iphone 6plus - Text box in Lock screen

I recently noticed that my lock screen has got a new text box to enter my security PIN. I also see a OK button next to text box in the lock screen which I did not see after the last OS upgrade. I've made no OS upgrade recently and current version is at 9.3.1 (13E238) (Model: MGA82HN/A).

Is it something normal ? I remember that this text box came up after I tried to install Citrix Mobile Workstyle to configure my office mailbox. Is this a problem ? What should I do to restore back to the normal or Original screen (without text box and OK button).