If i accidently hit the refile button can I just close the program and not submit the changes

Yes, if you accidentally hit the ReFile button when you do not want to do a refile, simply close out of that open return. You should then be able to "delete" the return that is called "ReFile of XXX XXXXX" so you do not mistakenly open it again and do the actual ReFile.

If you cannot delete it right away, you may have to open and close another return so the ReFile is not the last one worked on.

I am filing joint tax return and my one was originally accepted but accidentally hit refile for my husbands. I do not want to refile but I seem not to have any other choice

As long as you don't proceed to the filing stage of the ReFile, then it will not be sent to the CRA. You can delete the ReFile as per TurboTaxKim's instructions above.