Verification Code Failure

I'm the administrator of a group of users. One of them put her cell phone for the verification code, but there is something wrong and she is not able to get the code anymore.

Now everytime she tries to access the account she is asked the verification code, and as she is unable to provide it, the system asks her to contact her administrator (me), and I haven't found a way to disable it in the control panel. Please help me.

Thanks