Required signature field is being bypassed.

We also requested signature in the form it has been bypassed.

I made tests on your form http://www.jotform.co/form/52288329496873 and it seems that I am unable to bypass the required signature field. I will not be able to submit the form unless I fill in the signature field.

The user might have been able to bypass the signature field due to their browser's javascript being disabled/turned off. The required fields are checked using javascript, and as such if they are disabled, then the user will be able to submit the form even if a required field is not filled. To prevent the user from submitting the form if their javascript is disabled, you may add the NoScript Widget to your form. 

When this widget is added to the form, it will conditionally hide the entire form and display the message you defined when JavaScript is disabled in their browser.

If you need further assistance, please let us know.
Regards.