How unencrypted and reencrypt form

You should get the encryption wizard while viewing the submissions of your form, this will happen as long as encryption is enabled on your form settings. Now, if you turn off encryption you will not get the wizard and the already encrypted submissions will not be readable. Note that it's not possible to decrypt the data without the correct key. 

I would recommend you to check the following guide where you will find more information about encryption: https://www.jotform.com/help/344-Encrypted-Forms-and-How-to-Use-Them 

If you have more questions, let us know.